This study was designed to determine the levels and predictors of Medicare enrollees' satisfaction with access to medical care and quality of health care in a health maintenance organization. Data collected by an instrument adapted from the Group Health Association of America's Consumer Satisfaction Survey were analyzed after being linked with administrative data. In general, Medicare enrollees reported high satisfaction with both access to and quality of health care. Most members (96%) rated skill, experience, and training of physicians and the friendliness and courtesy of the staff favorably. A lower percentage of members (77%) rated favorably the ability to contact a physician after hours. Levels of satisfaction were essentially not explained by patient characteristics such as age, sex, geographic region, medications, or utilization. Stepwise regression identified the ease of arranging appointments as the strongest predictor of satisfaction, with access to care and outcomes of medical care as the strongest predictor of overall satisfaction with quality of health care. These findings indicate that items that members rated least favorably, such as ability to contact a physician after hours, added little to the prediction of satisfaction with access to and quality of health care.