2006 Healthcare Conference Citigroup 2006 Healthcare Conference March 1, 2006

Forward-Looking Statements 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.

Our Value Proposition: Complete Alignment To reduce pharmacy costs, without compromising health outcomes, while maximizing patient satisfaction

The Art of Trend Management -- Alignment High Performance Formulary Restricted Retail Network Ability to manage trend Exclusive Home Delivery Specialty Pharmacy Step Therapy Generic Utilization Programs 3-tier 2-tier Plan sponsor appetite for innovative clinical tools As Plan Sponsors Take Advantage of Our Tools to Better Mange Trend, The Better We Perform

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

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

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

Q4 2005 Highlights Adjusted EPS of $0.77*, up 45% from $0.53 last year For 2005, adjusted EPS of $2.60*, up 34% from 2004 Cash flow from operations of $262 M vs. $193 M last year For 2005, cash flow of $793 M vs. $496M in 2004 Gross profit of $364 million, up 38% Gross profit per adjusted claim was $2.54, up 34% EBITDA of $220 M, up 42% EBITDA per adjusted claim was $1.53, up 37% * Reconciliation of reported EPS to adjusted EPS is included in Table 4 of the 4Q 2005 earnings release

Quality of Earnings (5) (1) (4) (4) (3) (2) Reflects a $70-$75 million reduction in Q2 2003 due to one-time impact of implementing a new wholesale purchase agreement Excludes a $0.04 per share charge for the early retirement of debt Excludes a $0.10 charge to increase legal reserves for the cost of defense. Excludes an $0.08 and $0.02 prior year tax benefit in Q2 and Q3, respectively Excludes a $0.02 charge for the early retirement of debt * Reflects a 12-month moving average of free cash flow (cash from operations less CapX)

Profits Per Claim Growth EBITDA* per adjusted claim 10% CAGR*** 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. * 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. *** Based on 2005 average EBITDA per adjusted Rx of $1.29

Claims Volume Vs. EPS Growth Expanding Margins Supports Strong EPS Growth on More Modest Claims Growth (5) (3) (2) (1) (4) Excludes a $0.10 charge to increase legal reserves (4) Reflects the June 1st anniversary of the DoD retail contract Excludes an $0.08 prior year tax benefit (5) Excludes a $0.02 charge for early retirement of debt Excludes a $0.02 prior year tax benefit

Focus on Return on Invested Capital (ROIC) * Reflects operating income less tax divided by average invested capital, which consists of stockholder’s equity, plus interest bearing liabilities plus long-term deferred income taxes, net. ** Excludes $25 million charge to increase legal reserves for the cost of defense and 5.5 million termination payment received ROIC is our Preferred Performance Metric

Ed Ignaczak Senior Vice President Sales and Account Management Express Scripts’ Value Proposition Multi-Faceted Growth Growth through…. Improving Client Satisfaction Expanding Value Prop with Existing Clients Capturing New Business Ed Ignaczak Senior Vice President Sales and Account Management

Multiple Factors being leveraged to drive Client/Shareholder Value New Sales ESI and Client Values are Aligned $ Value to ESI / $ Value to Clients Pipeline Pipeline Specialty Specialty Specialty Generics Generics Generics Generics Home Delivery Home Delivery Home Delivery Home Delivery Home Delivery Satisfaction Satisfaction Satisfaction Satisfaction Satisfaction Satisfaction # of Leveraged Factors We can move the market…….

Client Satisfaction continues to improve.. Increases were recognized in all categories with Likelihood to Recommend making the largest jump during 2005.

Very Satisfied Clients Buy More Services and Promote ESI to others. A 2004 Harvard Business Review article asserted that "net promoter scores," which measure the difference between the percentage of customers who give the highest Willingness to Refer ("promoters") and those who give low scores ("detractors"), correlate closely with a company's revenue growth. CAGR = 5.1% CAGR = 10.8% EBITDA Drivers: Increased Mail Penetration Generics Specialty People / Talent

Significant Upside opportunities: Home Delivery Room to Grow! Improved Margin Opportunity Home Delivery % of Total Adj. Rx DoD-TRRx Many initiatives focusing on driving to higher margin mail volumes. DoD-TMOP 2006 Projected 9.6% CAGR

Significant Upside opportunities: Generic Usage $43B in Brand Drugs losing patent protection ’06 - 09. Industry Savings Opportunity Class Actual Generic Fill Rate Generic Targets Gap Potential Savings @ Target Gastrointestinal 31% 95% 64% $5.4 Billion Antihyperlipidemics 7% 70% 63% $5.1 Billion Calcium Channel Blockers 43% 90% 47% $484 Million Antihypertensive 48% 75% 27% $2.0 Billion NSAIDs 85% 38% $3.9 Billion Anti-depressants 41% 34% $3.2 Billion Total Savings $20 Billion ESI Generic Fill Rate

Significant Upside opportunities: Specialty Market Opportunity ’05-’09 Book of Business Penetration Specialty Drugs Under Development Curascript CAGR = 405%

Case Study: Actual ESI Client Unmanaged Spend Cumulative Savings $19.2m Managed Spend Renewal Rates Implemented Clinical Programs Mail Education Generics Incentives High Performance Formulary Specialty Clinical Programs ESI Value to client increased over time creating aligned benefits for both client and ESI.

Client Demand for Trend Management products/services drives EBITDA. Up Sell Mail, Generics and Specialty

Multiple Factors Driving New Sales Success When a large Employer changed PBM’s in 2005, they selected Express Scripts 72% of the time! Sold! Coverage/Quality Strategic Acquisitions $ in Sites/ Tech Expert Consultation Lowest Net Cost

2006 New Sales Pipeline

Book of Business Dynamics Recent Fortune 100 Wins and Market Dynamics are altering the composition of our Book of Business. A combination of increased Rx/Life and services per client driving higher EBITDA/client and EBITDA/claim. Rx / Life EBITDA / Rx CAGR = 3.5% CAGR = 4.3%