JP Morgan 24 th Annual Healthcare Conference

1. JP Morgan 24th Annual Healthcare Conference January 9, 2006

2. 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.

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

4. Unmanaged Prescription Drug Trend Source: 2004 Drug Trend Report Plan sponsors will likely increase the use of PBM tools to manage drug spend

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

6. $50 $60 $70 $80 Alignment - Building a Formulary • Evaluate relative clinical value • Determine net cost Drug A Drug B Relative clinical value Drug C Cost per prescription

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

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

9. Most cost effective Most cost effective Drug B Drug A Drug A Drug B Relative clinical value Drug C Drug C $50 $60 $70 $80 Cost per prescription Alignment - Building a Formulary • Evaluate relative clinical value • Determine net cost • Account for market share • Account for rebates • Select formulary products Exception: Market dynamics might “trump” net cost

10. Impact on Client Impact on Client Impact on Patient Impact on Patient Impact on ESI Impact on ESI Lower drug cost Lower drug cost Lower co payment Lower co payment Higher Profit/Rx Higher Profit/Rx More choice More choice More Flexibility Alignment - Retail Network Management Greater Management

11. Alignment – Clinical Programs Plan Designs Encourage Greater Use of Generics and Preferred Low-cost Brands Clients using step therapy realize on average a 2 percentage point increase in generic utilization

12. Alignment – Home Delivery We Offer Highly Efficient, Cost-effective Home Delivery

13. Alignment – Growing Demand for Home Delivery Increased home delivery penetration Excludes UHC claims * Represents network claims plus 3 times home delivery claims –home delivery claims are 90 days vs. 30 days in the network. • ** Twelve months ended Sept 2005 Home Delivery Helps Manage the Cost of Maintenance Drugs

14. Alignment – Generic Utilization Express Scripts Leads in Generic Utilization Source: From public filings

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

16. Alignment – Specialty Pharmacy Traditional Spend $210 Billion Specialty Spend $35 Billion 2004 Total Outpatient Pharmacy Spend $190 Billion Specialty Spend $73 Billion 26% 18% 2008 Projected Outpatient Pharmacy Spend $283 Billion Traditional Spend $155 Billion Sources: IMS Data through November 2004 Wall Street Equity Research, 2004 CMS National Healthcare Expenditure Projection: 2003 – 2013 Data on file: CuraScript. Clients are Seeking Solutions for High-cost Specialty Drugs

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

18. 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)

19. What Are the Savings? Retail, Clinical. Formulary And Rebate Savings 24% Paid by Cash Customer at Pharmacy Retail Pharmacy Cash Price Home Delivery Savings 6% 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)

20. Increased Savings Opportunities: Client Member Increased Profit Opportunities: 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 Retail Non-pref. Brand Retail Pref. Brand Mail Pharmacy Generics Alignment – A Win-Win-Win Proposition We make money by saving clients and members money

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

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

23. 2006 Upsell Pipeline is Strong 10,000 • 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 Sold Weighted Pipeline 9,000 8,000 7,000 6,000 ('000 Lives) 5,000 4,000 3,000 2,000 1,000 0 Home Delivery Three Tier Generic Enforcement Specialty/CuraScript New Clinical Products Narrowing Formularies As of April 2005

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

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

26. Q3 2005 Highlights • Adjusted EPS of $0.67*, up 34% from $0.50* last year • Cash flow from operations of $214.6 M vs. $150.0 M last year • Repurchased 4.0 million shares for $219.9 million • Generic drugs were 55% of total prescriptions vs. 51% last year • Gross profit of $293.2 M, up 25% • Gross profit per adjusted claim was $2.13, up 20% • EBITDA per adjusted claim was $1.32, up 19% • Raised EPS guidance for 2005 • Provided 2006 EPS guidance of $3.10 to $3.22 *Excludes prior period tax benefit of $0.01 in Q3 2005 and non recurring charge of $0.10 for legal defense costs in Q3 2004 – reconciliation of reported EPS to adjusted EPS is included in Table 4 of the 3Q 2005 earnings release

27. Quality of Earnings (4) (1) (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 $0.01 prior year tax benefit in Q2 and Q3, respectively * Reflects a 12-month moving average of free cash flow (cash from operations less CapX)

28. Components of EPS Growth — 2004 2004 6% 7% 8% * Excluding $25 million charge to increase legal reserves for the cost of defense and $5.5 million termination payment received

29. Major PBM Prescription Growth Note: Rx growth for Medco, Caremark reflect as configured today * YTD 9-30-05

30. Claims Volume Vs. EPS Growth Expanding Margins Supports Strong EPS Growth on More Modest Claims Growth (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 Excludes a $0.01 prior year tax benefit

31. Profits Per Claim Growth EBITDA* per adjusted claim 11% 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.

32. Gross Profit* / SG&A* / EBITDA 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. Future EBITDA per Adj. Rx Must Come From Gross Profit per Adj. Rx

33. Components Of EPS Growth

34. 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

35. Why Express Scripts? Industry-Leading ROIC We Lead Our Peer Group in ROIC Performance Source: Express Scripts Analysis

36. Peer Group Total Return - 2005 Peer group avg. 32.4% ESI’s 119% return is more than 3.5 times our peer group

37. 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

38. 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 acquisitionshave enhanced our value proposition