Sierra Health Services, Inc. A Managed Care Company

1. Sierra Health Services, Inc.A Managed Care Company Updated 3/12/07

2. Cautionary Statement Statements in this presentation and verbal statements made by representatives of Sierra that are not historical facts are forward-looking and based on management’s projections, assumptions and estimates; actual results may vary materially. Forward-looking statements are subject to certain risks and uncertainties, which include but are not limited to: • potential adverse changes in government regulations, contracts and programs, including the Medicare Advantage program, the Medicare Prescription Drug Plan and any potential reconciliation issues, Medicaid and legislative proposals to eliminate or reduce ERISA pre-emption of state laws that would increase potential managed care litigation exposure; • competitive forces that may affect pricing, enrollment, renewals and benefit levels; • unpredictable medical costs, malpractice exposure, reinsurance costs, changes in provider contracts and inflation; • impact of economic conditions; • changes in healthcare reserves; • the effects of the termination of the HCA contract; • variations from actuarial assumptions that can lead to higher than expected medical costs; • costs and losses from our enhanced Medicare Part D Prescription Drug Program product offering that we cannot yet project and • the amount of actual proceeds to be realized from the note receivable related to the sale of the workers’ compensation insurance operation. Further factors concerning financial risks and results may be found in documents filed with the Securities and Exchange Commission and which are incorporated herein by reference. Consequently, all of the forward-looking statements made in this presentation or verbally by representatives of Sierra are qualified by these cautionary statements, and there can be no assurance that the actual results or developments anticipated by Sierra will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, Sierra or its business or operations. Sierra assumes no obligation to update publicly any such forward-looking statements, whether as a result of new information, future events or otherwise.

3. Disclosure Statement This presentation includes the following non-Generally Accepted Accounting Principle (GAAP) measures • Medical care ratio excluding PDP • Days in claims payable excluding PDP which under SEC Regulation G we are required to reconcile with GAAP.

4. Recent Merger Announcement • Sierra signed a definitive agreement to be acquired by United Health Group • $43.50 per share in cash • Total equity value of $2.6 billion

5. Nevada Health Insurance Demographics (1) U.S. Census Bureau (2005) -Total Nevada Population = 2,448,000 (2) Nevada State Health Division, HMO Industry Profile 9/30/06

6. HMO Membership (in thousands) 9.9% CAGR 396 365 330 292 272

7. Commercial HMO Sales Growth December 31, 2006 Commercial HMO Members: 279,100 • 9.8% Net Commercial Growth in 2006 • Expect 3-5% Net Commercial Growth in 2007 • Only 19% HMO Penetration Statewide(1) (1) Nevada State Health Division, HMO Industry Profile 9/30/06

8. Health Plan of NevadaMembership Characteristics(1) December 31, 2006 Commercial Employer Type Mix Commercial Employer Group Size (1) Based on number of subscribers in each category

9. Commercial Costs • 2007 Projected Cost Trends • Contracted Hospitals 3 - 6% (1) • Physician 4 - 5% • Pharmacy 5 - 9% • Overall 5 - 7% (1) (1) Does not include any impact from increased costs related to non-contracted hospitals

10. Commercial Pricing • 2007 Projected Rate Increases • HMO 3 – 5% • POS 5 – 7% • PPO 7 – 9% • Overall 5 – 6%(1) (1) Includes benefit reductions (buydowns) which increase the expected yield by approximately 1%

11. Medicare Sales Growth December 31, 2006 Medicare Advantage (1) Members: 58,600 • 3.9% Net Medicare Growth for 2006 • Expect 3-5% Net Medicare Growth for 2007 • Minimal yield increase for 2007 • Only 32% Medicare HMO Penetration Statewide (2) (1) Medicare Advantage includes both HMO and PPO Members (2) Nevada State Health Division, HMO Industry Profile 9/30/06

12. Medicare Costs • 2007 Projected Cost Trends • ContractedHospitals 3 - 6% (1) • Physician 3 - 4% • Pharmacy 6 - 8% • Overall 3 - 5% (1) (1) Does not include any impact from increased costs related to non-contracted hospitals

13. Prescription Drug Plan – Part D December 31, 2006 Stand-alone PDP members:184,900 • Stand-alone PDP 2007 • 30 states and the District of Columbia • Auto-enrollment provider in AZ, CA(1), CO, ID, NV(1), OR, UT, WA • Limited marketing effort • Projected approximately 85% MCR on basic plan • Expect pre-tax income of $11-14 million(2) • Will not receive new auto-enrollees for 2007 • Earnings from basic plan only

14. Prescription Drug Plan – Part D January 2007 Enhanced Benefits Plan: 37,000 members • 30 states and the District of Columbia • $93 average member contribution; $170 per member average premium • Plan includes generic and brand prescription coverage in the “donut hole” • Expect to incur loss on product in 2007 based on January claims data • Expect to be able to develop a range of the projected loss within 45 to 60 days

15. Medicaid December 31, 2006 Medicaid Members: 60,500 • Mandatory 2 Plan Market in Nevada • Currently Serving CHiPS, TANF, CHAP • +50% Medicaid HMO Market Share in Nevada (1) • Expect Medicaid membership to remain flat in 2007 • Expected 2007 rate increase flat for the first half of 2007; 1% increase in the second half of 2007 • New contract effective 11/1/06 through 6/30/09 with DHCFP option to extend the contract for an additional two years (1) Nevada State Health Division, HMO Industry Profile 9/30/06

16. Nevada Medicaid Market Share (HMO)(1) (1) Nevada State Health Division, HMO Industry Profile September 30, 2004, 2005 and 2006

17. HPN Medicaid Revenue Growth (in millions) 20.8% CAGR

18. Medical Subsidiaries Clinical Overview Medical Subsidiaries Southwest Medical Associates (SMA) Family Healthcare Services (FHS) Family Home Hospice (FHH) Total Home Care of Nevada (THC) Behavioral Healthcare Options (BHO) • Multi-specialty physician group • 250 Providers • Provides care services in patient’s home • Medicare certified home health agency • Hospice servicing terminally ill patients • Medicare certified • Home care products, infusion therapy services, and specialty drugs • DME • Specialized mental health/substance abuse services. • URAC accredited

19. Hospital Update • Extended two of three largest hospital provider contracts, one through the middle of 2008 and the other through the end of 2009 • Contracts are evergreen thereafter and require 180 days written notice for termination • HCA contract ended 12/31/06 • Within coverage constraints, we are not authorizing non-emergency procedures at HCA facilities. • Preliminary results have been positive

20. Medical Premium Revenue Trends ($ in millions) 17.1% CAGR (1) (1) Includes $197.1 million in PDP revenue

21. Consolidated MCR

22. Consolidated MCRExcluding PDP

23. Consolidated Medical Expenses Twelve Months Ended 12/31/06

24. Consolidated Medical Expenses Excluding PDP (1) Twelve Months Ended 12/31/06 (1) Excludes PDP medical expenses of $160.3 million

25. Operating Income Managed Care and Corporate Operations Segment ($ in millions) 36.0% CAGR

26. Consolidated Pretax Margin Managed Care and Corporate Operations Segment

27. Cash and Investments From Continuing Operations ($ in millions) $428.4 $382.5 $388.6 $337.8 $250.0

28. Total External Debt From Continuing Operations ($ in millions) (1) (1) $75 million outstanding on line of credit and converted $21.7 million in debentures on January 18,2007

29. Senior Convertible Debentures • $115 MM original issue on March 15, 2003 • 2.25% coupon rate • $21.8 million outstanding as of January 31, 2007 • Issued 10.2 million shares upon conversion • Expensed approximately $1.5 million in prepaid interest for conversion in 2005, $176,000 in 2006 and $601,000 in 2007 • Expensed deferred financing costs of $1.2 million in 2005, $91,000 in 2006 and $176,000 in 2007

30. Managing Dilution(1) (shares in millions) -5.3% CAGR 68.0 65.3 61.0 (1) Adjusted to reflect 2-for-1 stock split effective December 30, 2005

31. Share Repurchases from 1/1/03 (1) • Repurchased 29.1 million shares as of 1/30/07 • $22.24 average repurchase cost as of 1/30/07 • Current bank agreement allows for unlimited share repurchases • Based on meeting the required leverage ratio • $57.1 million available for repurchases as of 1/30/07 • Includes $50 million approved by Board of Directors on 1/25/07 (1) Adjusted to reflect 2-for-1 stock split effective December 30, 2005

32. Strategic Objectives • Achieve Commercial Premium Yields of 4 to 5% before benefit buydowns • Achieve Commercial Unit Growth of 3 to 5% • Manage appropriately out of network hospital costs • Implement Medicare Advantage Expansion, including Private Fee-For-Service plan. • Manage an expected increase in consolidated MCR of 150 to 200 bps(1) • Achieve EPS of $2.30 to $2.40 excluding the impact of the expected potential loss on the enhanced PDP offering (1) Excludes PDP

33. Reconciliation of non GAAP measuresMedical care ratio (excluding PDP)(1) (1) The Company believes that reflecting the ratio excluding the effects of the PDP provides a more comparable measure of our medical care ratio to our historical results.

34. Reconciliation of non GAAP measuresDays in claims payable (excluding PDP) (1) The Company believes that reflecting days in claims payable excluding the effects of the PDP provides a more comparable measure to our historical results.

35. Sierra Health Services, Inc.A Managed Care Company Updated 3/12/07