1. Lehman Brothers 9th Annual Global Healthcare Conference March 8, 2006

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 Today’s Challenging Environment: Maintaining Access to Safe and Affordable Drugs

4. 4 Unmanaged Prescription Drug Trend Plan Sponsors Will Likely Increase the Use of PBM Tools to Manage Drug Spend Source: 2004 Drug Trend Report

5. 5 Our Value Proposition: Complete Alignment To reduce pharmacy costs, without compromising health outcomes, while maximizing patient satisfaction

6. 6 Ability to manage trend 2-tier 3-tier Step Therapy Exclusive Home Delivery As Plan Sponsors Take Advantage of Our Tools to Better Mange Trend, The Better We Perform The Art of Trend Management -- Alignment High Performance Formulary Restricted Retail Network Generic Utilization Programs Specialty Pharmacy Plan sponsor appetite for innovative clinical tools

7. 7 1.Evaluate relative clinical value Cost per prescription Alignment - Building a Formulary Drug A Drug B Drug C $60$50$70$80 Relative clinical value

8. 8 1.Evaluate relative clinical value 2.Determine net cost Cost per prescription Alignment - Building a Formulary Drug A Drug B Drug C $60$50$70$80 Relative clinical value

9. 9 Cost per prescription Drug A Drug B Drug C Most cost effective Relative clinical value $50$60$70$80 Alignment - Building a Formulary 1.Evaluate relative clinical value 2.Determine net cost 3.Account for market share A B C

10. 10 1.Evaluate relative clinical value 2.Determine net cost 3.Account for market share 4.Account for rebates Cost per prescription Relative clinical value $50$60$70$80 Drug A Drug B Drug C Most cost effective Alignment - Building a FormularyAB CAB

11. 11 1.Evaluate relative clinical value 2.Determine net cost 3.Account for market share 4.Account for rebates 5.Select formulary products Cost per prescription Relative clinical value $50$60$70$80 Drug A Drug B Drug C Most cost effective Drug C Drug A Drug B Most cost effective Alignment - Building a Formulary Exceptions: * Market dynamics can trump net cost * High Performance Formulary A B C

12. 12 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 Formulary Management 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

13. 13 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

14. 14 ESI Analysis Our Clients and Members Will Benefit From a Growing Generic Opportunity Alignment – Growing Generic Opportunity

15. 15 Impact on ClientImpact 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

16. 16 Alignment – Specialty Pharmacy 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 26% 18% Traditional Spend $210 Billion Specialty Spend $73 Billion Specialty Spend $35 Billion Traditional Spend $155 Billion 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

17. 17 Express Scripts’ Specialty Penetration Has Increased from 2% to 36% in the First 2 Years of the CuraScript Acquisition. Percentage of Plan Costs Source: Express Scripts Analysis. CuraScript Penetration into Express Scripts

18. 18 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

19. 19 * Represents network claims plus 3 times home delivery claims –home delivery claims are 90 days vs. 30 days in the network. Increased home delivery penetration Home Delivery Helps Manage the Cost of Maintenance Drugs Alignment – Growing Demand for Home Delivery Excludes UHC claims

20. 20 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% Home Delivery Savings 6% Paid by Express Scripts Clients Total Savings 30% COSTCOST Retail Pharmacy Cash Price Express Scripts Client Savings Express Scripts Client Costs

21. 21 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, home delivery and generics We Make Money by Saving Clients and Members Money Moving to preferred brands, home delivery and generics

22. 22 We Deliver Against Client and Patient Expectations: To make the use of prescription drugs safer and more affordable

23. 23 Client/Patient Focus By membership Health Plan Sponsors Recognize Express Scripts Single Focus on Making Prescription Drugs More Affordable Why Express Scripts? Alignment With Clients Trend management tools Generics Specialty

24. 24 Client Satisfaction continues to improve.. Increases Were Recognized in All Categories With Likelihood to Renew Showing the Largest Increase

25. 25 Our Financial Results Express Scripts has demonstrated a proven track record

26. 26 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

27. 27 Quality of Earnings (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 and $0.02 prior year tax benefit in Q2 and Q3, respectively (5)Excludes a $0.02 charge for the early retirement of debt (1) (2) * Reflects a 12-month moving average of free cash flow (cash from operations less CapX) (3) (4) (4) (5)

28. 28 Components Of EPS Growth

29. 29 Major PBM Prescription Growth Note: Rx growth for Medco, Caremark reflect as configured today

30. 30 Claims Volume Vs. EPS Growth (1)Excludes a $0.10 charge to increase legal reserves (4) Reflects the June 1 st anniversary of the DoD retail contract (2)Excludes an $0.08 prior year tax benefit (5) Excludes a $0.02 charge for early retirement of debt (3)Excludes a $0.02 prior year tax benefit (2) (3) (1) Expanding Margins Supports Strong EPS Growth on More Modest Claims Growth (4) (5)

31. 31 Profits Per Claim Growth 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. *** Based on 2005 average EBITDA per adjusted Rx of $1.29 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. 10% CAGR***

32. 32 Gross Profit* / SG&A* / EBITDA per Adj. Rx Future EBITDA per Adj. Rx Must Come From Gross Profit per Adj. Rx * Before depreciation and amortization ** Excluding $25 million charge to increase legal reserves for the cost of defense and $5.5 million termination payment received. Source: Express Scripts Analysis.

33. 33 Focus on Return on Invested Capital (ROIC) ROIC is our Preferred Performance Metric * 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

34. 34 Peer Group Total Return - 2005 ESI’s 119% Return Was More than 3.5 Times Our Peer Group Peer group avg. 32.4%

35. 35 S&P Total Return – 2005 Only 2 Companies in the S&P 500 Exceeded ESI’s Total Return to Stockholders of 119% in 2005 Note: Returns reflect stock price increase plus dividend yield

36. 36 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