| 1199SEIU in Winchester, CA | AMERIGROUP in Winchester, CA |
| APS Healthcare in Winchester, CA | Aetna in Winchester, CA |
| Alliance in Winchester, CA | AmeriHealth in Winchester, CA |
| American Behavioral in Winchester, CA | Beech Street in Winchester, CA |
| Behavioral Health Systems in Winchester, CA | BlueCross and/or BlueShield in Winchester, CA |
| CCN in Winchester, CA | CHIPA/College Health in Winchester, CA |
| Cascade Health in Winchester, CA | Ceridian in Winchester, CA |
| ChoiceCare in Winchester, CA | Cigna in Winchester, CA |
| ComPsych in Winchester, CA | Corphealth in Winchester, CA |
| Coventry in Winchester, CA | First Choice Health in Winchester, CA |
| First Health in Winchester, CA | GHI/Group Health Incorporated in Winchester, CA |
| Great-West in Winchester, CA | Guardian in Winchester, CA |
| HFN in Winchester, CA | HIP/Health Plan of New York in Winchester, CA |
| Harvard Pilgrim Health Care in Winchester, CA | Health Net in Winchester, CA |
| Holman Group in Winchester, CA | Horizon Healthcare in Winchester, CA |
| Humana in Winchester, CA | Integrated Health Plan in Winchester, CA |
| Interplan in Winchester, CA | Kaiser in Winchester, CA |
| LifeWise in Winchester, CA | MAMSI in Winchester, CA |
| MHN/Managed Health Network in Winchester, CA | Magellan Behavioral Health in Winchester, CA |
| MagnaCare in Winchester, CA | Medica in Winchester, CA |
| Medicaid in Winchester, CA | Medical Mutual in Winchester, CA |
| Medicare in Winchester, CA | Multiplan in Winchester, CA |
| NCPPO in Winchester, CA | ODS in Winchester, CA |
| Oxford in Winchester, CA | PHCS/Private Health Care Systems in Winchester, CA |
| PPOM in Winchester, CA | PacifiCare in Winchester, CA |
| PacificSource in Winchester, CA | PreferredOne in Winchester, CA |
| Providence in Winchester, CA | Sloans Lake in Winchester, CA |
| TRICARE in Winchester, CA | TriWest0127 in Winchester, CA |
| Tufts in Winchester, CA | UniCare in Winchester, CA |
| Uniform in Winchester, CA | United in Winchester, CA |
| VMC in Winchester, CA | ValueOptions in Winchester, CA |
| WellPoint in Winchester, CA |