Banc of America 35 th Annual Investment Conference

1. Banc of America 35th Annual Investment Conference Sept 19, 2005

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

4. More Number of Drugs Fewer Benefit Options 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 Lowest Overall Cost Closed

5. 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

6. 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

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

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

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

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

11. Oncology $12.6 36% HIV/AIDS 3.4 10% Renal 3.2 9% Hemophilia 1.6 5% Hepatitis C 1.6 5% Transplant 1.5 4% Multiple sclerosis 1.5 4% Rheumatoid arthritis 1.5 4% RSV prophylaxis 0.6 2% Infertility 0.5 1% Growth Hormone 0.5 1% Other 3.5 19% Total $35 100% Alignment – Specialty Pharmacy Billions Specialty Market 2004 Source: ESI Analysis Clients are Seeking Solutions for High-cost Specialty Drugs

12. 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.

13. 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)

14. 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)

15. 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

16. Average Annual Drug Spend Among Medicare Population Source: Actuarial Research Corporation PBM’s Are Part of the Solution for Medicare • ESI is well positioned for 2006 • Our 2006 offensive strategy is to help our managed care and carrier clients profitably grow their MA-PDs and PDPs • We are building the foundation for 2007 The Medicare Prescription Drug Act will shape the direction of our industry for years to come

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

18. 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

19. 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

20. 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

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

22. 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

23. Financial Overview Quality of Earnings (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 prior period benefit related to state tax planning strategies * Reflects a 12-month moving average of free cash flow (cash from operations less CapX)

24. 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

25. Financial Overview EBITDA* per adjusted claim 9% 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. *** 2Q ‘05

26. Gross Profit/SGA/EBITDA per Adj. Rx Future EBITDA per Adj. Rx Must Come From Gross Profit per Adj. Rx • * Excluding $25 million charge to increase legal reserves for the cost of ** 2Q 2005 defense and $5.5 million termination payment received.

27. 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

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

29. 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