The main health maintenance organization providers in California include Kaiser Permanente, Blue Shield of California, Anthem Blue Cross and Cigna as of 2015, according to the California Office of the Patient Advocate. Aetna Health of California and Sharp Health Plan are also among the top-10 HMO providers.
The Kaiser Permanente HMOs of Northern and Southern California received four stars, the highest rating, for providing recommended care and positive patient experiences, notes the California Office of the Patient Advocate. Blue Shield of California and Sharp Health Plan received four stars for providing positive patient experiences and three stars for providing recommended care. Anthem Blue Cross, Cigna and Aetna Health of California received three stars in both categories.