1. 1 Bear Stearns 18 th Annual Healthcare Conference Sept 13, 2005

2. 2 Statements included in this presentation or in the oral comments made as part of this presentation may contain forward-looking statements, including but not limited to statements of the Company’s plans, objectives, expectations or intentions, that involve risk and uncertainties. The Company’s actual results may differ significantly from those projected or suggested in any forward-looking statement due to a variety of factors, which are discussed in detail in the Company’s filings with the Securities and Exchange Commission. Forward-Looking Statements

3. 3 Our Interests are Aligned with Clients and Patients: To make the use of prescription drugs safer and more affordable

4. 4 More Number of Drugs Fewer Benefit Options Impact on ClientImpact on PatientImpact on ESI Lower drug cost More choice Lower co payment More choice Higher Profit/Rx More Flexibility Alignment –Formulary Management Therapy Class We Provide Flexible Management of the Supply Chain 1. Select number of drugs in therapy class 2. Determine formulary control 3. Drive towards lowest overall cost # of drugs # of drugs # of drugs Open Differential Co-pay Closed Lowest Overall Cost

5. 5 Alignment - Retail Network Management States Available Pharmacies Most Inclusive Network Most Restrictive Network TRICARE Access Minimum CA 5,6445,0713,881283 NY 4,4444,2241,829300 TX 4,2363,8211,827579 FL 4,0203,6701,966469 PA 2,9702,8251,687432 Greater Management Higher Profit/Rx More Flexibility Lower co payment More choice Lower drug cost More choice Impact on ESIImpact on PatientImpact on Client Higher Profit/RxLower co paymentLower drug cost Impact on ESIImpact on PatientImpact on Client

6. 6 Impact on PatientImpact on ESI Lower drug costLower co paymentHigher Profit/Rx Alignment – Clinical Programs Clients using step therapy realize on average a 2 percentage point increase in generic utilization Plan Designs Encourage Greater Use of Generics and Preferred Low-cost Brands

7. 7 Alignment – Home Delivery Impact on ClientImpact on PatientImpact on ESI Lower drug cost Choice Lower co payment Choice Higher profit/Rx We Offer Highly Efficient, Cost-effective Home Delivery

8. 8 * Represents network claims plus 3 times home delivery claims –home delivery claims are 90 days vs. 30 days in the network. Excludes UHC claims Increased home delivery penetration Home Delivery Helps Manage the Cost of Maintenance Drugs Alignment – Growing Demand for Mail

9. 9 Alignment – Generic Utilization Impact on ClientImpact on PatientImpact on ESI Lowest drug costLowest co paymentHighest profit/Rx Source: From public filings Express Scripts Leads in Generic Utilization

10. 10 ESI Analysis Represents over 20% of 2004 branded drug sales Our Clients and Members Will Benefit From a Growing Generic Opportunity Alignment – Growing Generic Opportunity

11. 11 100%$35 Total 19%3.5Other 1%0.5Growth Hormone 1%0.5Infertility 2%0.6RSV prophylaxis 4%1.5Rheumatoid arthritis 4%1.5Multiple sclerosis 4%1.5Transplant 5%1.6Hepatitis C 5%1.6Hemophilia 9%3.2Renal 10%3.4HIV/AIDS 36% $12.6Oncology Alignment – Specialty Pharmacy Specialty Market 2004 Billions Source: ESI Analysis Impact on Client Impact on Patient Impact on ESI Lower drug cost Lower co payment Higher profit/Rx Improved reporting Improved quality of care Higher client satisfaction Clients are Seeking Solutions for High-cost Specialty Drugs

12. 12 2006 Upsell Pipeline is Strong Significant potential to continue to manage client trends in key product categories New products continue to be developed and rolled out Strong track record of success 10,000 ( '000 Lives) 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 Home Delivery Generic Enforcement Narrowing Formularies New Clinical Products Specialty/CuraScript Three Tier Sold Weighted Pipeline

13. 13 What Are the Savings? Availability of Proven PBM Cost Management Tools Will Produce 20%–25% Savings (CBO) Paid by Cash Customer at Pharmacy Retail, Clinical. Formulary And Rebate Savings 24% Mail Savings 6% Paid by Express Scripts Clients Total Savings 30% COSTCOST Retail Pharmacy Cash Price Express Scripts Client Savings Express Scripts Client Costs

14. 14 Alignment – A Win-Win-Win Proposition Retail Non-pref. Brand Retail Pref. Brand Generics Mail Pharmacy Increased Savings Opportunities: Client Member Increased Profit Opportunities: Express Scripts Moving to preferred brands, mail and generics We make money by saving clients and members money Moving to preferred brands, mail and generics

15. 15 Client Satisfaction Steadily Improving Service and satisfaction metrics have increased consistently quarter over quarter since 2003 with an early spike in 2005 Exceed 60% 65% 70% 75% 80% 85% 90% 95% 100% ESI Performance Expectations Likelihood to Recommend Likelihood to Renew 2003 2004 1q05

16. 16 Our Financial Results Express Scripts has demonstrated a proven track record

17. 17 Financial Overview Q2 2005 Highlights – Adjusted EPS of $0.60*, up 30% from $0.46* last year – Cash flow from operations of $178.3 M vs. $55.5 M last year – Generic drugs were 54% of total prescriptions vs. 50% last year – Gross profit of $276.7 M, up 24% Gross profit per adjusted claim was $1.96, up 10% EBITDA per adjusted claim was $1.19, up 4% – Raised EPS guidance for 2005 *Excludes prior period tax benefit of $0.08 in Q2 2005 and non recurring charge of $0.04for early retirement of debt in Q2 2004 – reconciliation of reported EPS to adjusted EPS is included in Table 4 of the 2Q 2005 earnings release

18. 18 Financial Overview (1)Reflects a $70-$75 million reduction in Q2 2003 due to one-time impact of implementing a new wholesale purchase agreement (2)Excludes a $0.04 per share charge for the early retirement of debt (3)Excludes a $0.10 charge to increase legal reserves for the cost of defense. (4)Excludes an $0.08 prior period benefit related to state tax planning strategies Quality of Earnings (1) (2) * Reflects a 12-month moving average of free cash flow (cash from operations less CapX) (3) (4)

19. 19 Financial Overview EBITDA* per adjusted claim * A reconciliation of EBITDA to net income and to net cash provided by operating activities can be found in the Investor Relations section of Express Scripts’ Web site, www.express-scripts.com under Presentations. ** Excluding $25 million charge to increase legal reserves for the cost of defense and $5.5 million termination payment received. *** 2Q ‘05 Pricing can be lowered as clients tighten formulary compliance, increase home delivery, utilize generics and restrict retail networks. These changes result in lower prices to our clients and greater profits to Express Scripts. 9% CAGR

20. 20 Dom Meffe President and CEO, CuraScript Senior Vice President, Specialty Pharmacy Express Scripts’ Value Proposition Providing a Cost-Effective Solution for Specialty Drugs

21. 21 Specialty Pharmacy — The Gathering Storm Payers’ Dilemma: Looming Costs for Chronic Conditions Biotechnology Healthcare, April 2005 Biologics’ Looming Price Tag Has Payers Retooling Pharmacy Coverage Biotechnology Healthcare, April 2005

22. 22 What are Specialty Medications? High-cost oral, injectable, infused or inhaled medications Self-administered or administered by a healthcare provider Outpatient or a home setting

23. 23 Characteristics of Specialty Medications Frequent dosage adjustments More severe side-effects than traditional drugs Specialized storage, handling and distribution requirements Narrow therapeutic range Require periodic laboratory or diagnostic testing Cost in excess of $1,300 per 30 day supply

24. 24 Chemotherapy 32% Chemotherapy Supportive Care 15% Multiple Sclerosis 9% Rheumatoid Arthritis 8% Psoriasis 12% Hepatitis C 7% Growth Hormone Deficiency 3% RSV 10% IVIG 1% Hemophilia 3% National Specialty Product Mix $12.53 PMPM

25. 25 Biotech - Rapid Growth Sources: IMS Data through November 2004 Wall Street Equity Research, 2004 CMS National Healthcare Expenditure Projection: 2003 – 2013 Data on file: CuraScript. 2004 Total Outpatient Pharmacy Spend $190 Billion 2008 Projected Outpatient Pharmacy Spend $283 Billion Source: PhRMA, International Federation of Pharmaceutical Wholesalers & Biotech Industry Organization 26% 18% Traditional Spend $210 Billion Specialty Spend $73 Billion Specialty Spend $35 Billion Traditional Spend $155 Billion Biotech Drugs in Development Biotech Drugs on the Market 2005 Estimated 2000 19951990 600 500 400 300 200 100 0 600 197 369 92 240 29 100 10 Number of Drugs

26. 26 Routes of Administration Specialty Drug Pipeline Late-stage development; Phase II or later Majority are injectable Oncology 17 46 2615*4** Rheumatoid Arthritis 5 20 875 Hepatitis C 5 9 81 Crohn’s Disease 2 10 172 Psoriasis 8 2312 Multiple Sclerosis 7 7 52 Oral Injectable IV SQ IM Unknown Source: Express Scripts data

27. 27 Current Distribution Channels Today’s Wild, Wild West Typical Payer Injectable Spend Retail Pharmacy 15%-20% Retail Pharmacy 15%-20% Mail Order Pharmacy 5%-10% Mail Order Pharmacy 5%-10% Specialty Pharmacy 5%-25% Specialty Pharmacy 5%-25% Physician Office 40%-60% Physician Office 40%-60% Outpatient Hospital 15%-20% Outpatient Hospital 15%-20% Home Care & Infusion 5%-10% Home Care & Infusion 5%-10% Unmanaged injectables result in: Inappropriate utilization Inconsistent clinical management Variable reimbursement Unmanaged injectables result in: Inappropriate utilization Inconsistent clinical management Variable reimbursement Higher cost for payer Reduced effectiveness of treatment Reduced patient care Reduced member satisfaction Physician panel frustration Higher cost for payer Reduced effectiveness of treatment Reduced patient care Reduced member satisfaction Physician panel frustration

28. 28 Our Specialty Solution CARE COST SAVINGS CONVENIENCE The CuraScript Difference Making specialty drug therapy more effective and affordable, one patient at a time

29. 29 Current cost 100 % CuraScript Value Proposition: A Legacy of Results

30. 30 Current cost Lower unit costs 7.2 % savings 100 % CuraScript Value Proposition: A Legacy of Results

31. 31 Current cost Lower unit costs 7.2 % savings Clinical based utilization savings 8.2 % savings 100 % CuraScript Value Proposition: A Legacy of Results

32. 32 Current cost Lower unit costs 7.2 % savings Clinical-based utilization savings 8.2 % savings 5.9 % savings 100 % CuraScript Value Proposition: A Legacy of Results Lower administrative costs

33. 33 Current cost Lower unit costs 7.2 % savings Clinical based utilization savings 8.2 % savings 5.9 % savings 100 % 21.3 % savings overall CuraScript Value Proposition: A Legacy of Results Lower administrative costs

34. 34 CARELogic™ Patient Care Management Tools of the program include: Patient assessment and risk stratification Integration of diagnostic and medical data Dedicated clinical patient support team Critical pathway management Intense patient education Adherence support for medication regimen compliance Psychosocial assessment and counseling Utilization and dose management Delivery coordination of medication Outcomes reporting Care management programs designed to specifically manage a disease state and the related drug therapy

35. 35 CARELogic ™ Clinical Management Initial Clinical Assessment Initial Clinical Assessment Disease Specific Clinical Pathway Initiated Disease Specific Clinical Pathway Initiated Ongoing Clinical Assessment and Interventions Ongoing Clinical Assessment and Interventions Patient Care Coordination Three follow-up interventions in the first six months High risk Clinical assessment and on- going interventions Patient Admission 01/11/05

36. 36 Proven Clinical Outcomes... CuraScript’s MSLogic™ Case Study 2004 Client Savings Avoided Exacerbation Expenses: $ 719,175.53 01/11/05 AverageCuraScriptNational Exacerbations Per Patient 0.671.0 Rate of Compliance92.2%54% 2004 Results of a 410,000 Life Health plan managed by CuraScript Marks, A.S., Johnson, KE; Value in Health, 2002;5. O'Brien et al, BMC Health Services Research, Sept. 2003 Clinical Management Strategies Goal: Reduce number and severity of relapses by improving patient compliance with their drug therapy Interventions: Patient assessment, education, utilization management, side effect management, physician consultation Translates into substantial impact on patient's quality of life and medical costs savings

37. 37 Implementation Expertise Program and Benefit Design Consultation Communication Strategy Ongoing Account Management Patient satisfaction Implement new programs Support to the client’s initiatives Continuous communication strategies  Client satisfaction

38. 38 CuraScript Client Network Mix Preferred 10% Mix 7% Open 43% Exclusive 40% As Percent of Total Revenue Source: Data on file

39. 39 Express Scripts’ specialty penetration has increased from 2% to 30% in the first 5.5 quarters of our CuraScript acquisition. Percentage of Plan Costs Source: Express Scripts Analysis. CuraScript Penetration into Express Scripts

40. 40 Priority Acquisition - Strategic Rationale  Creates one of the largest specialty franchises in the U.S. –$3+ billion annual specialty revenues –One of the fastest growing sectors in healthcare –Sector remains fragmented and market structure continues to emerge (greenfield opportunities)  Fills key therapy classes within CuraScript portfolio – “one-stop shopping for clients” –Infertility (number one fertility franchise) –Pulmonary Fibrosis –Pulmonary Hypertension –Home Infusion  Offers additional capabilities –Specialty distribution capabilities –Supply chain services  Leverages PBM core competencies (payor and manufacturer relationships, mail order pharmacies, clinical and trend management expertise) –Synergy potential –Increased value proposition for clients (single vendor, integrated reporting)

41. 41 Our Value Proposition Will Continue to Drive Growth Making the use of drugs safer and more affordable is more important than ever Plan sponsors will increasingly deploy our tools Express Scripts is well-positioned for sustainable growth Strong market fundamentals/new business opportunities Increased use of home delivery and generic drugs Growth in management of specialty pharmacy Productivity and capital structure improvements We have taken a different approach Alignment -- we make money by saving our clients money Strategic acquisitions have enhanced our value proposition

42. 42