Variation in the sociodemographic, system, and disease characteristics of Asians and Pacific Islanders compared with other ethnic groups and the quality of standard self-report measures of health and functioning by ethnic groups were examined. Secondary analysis of self-report data from the Medical Outcomes Study, an observational study of adult outpatients who received care in either prepaid or fee-for-service plans, was used to compare 527 Asians and Pacific Islanders to patients in other ethnic groups (16,989 whites, 2,533 African Americans, 1,009 Latinos, and 446 others). These patients all completed a screening questionnaire after visits with a Medical Outcomes Study clinician. Asians and Pacific Islanders were similar to African Americans and Latinos on most sociodemographic and system characteristics, disease status, and risk factors. Ethnicity was a significant predictor of differences in self-reported health. As a group, Asians and Pacific Islanders had better health or health of equal status compared with whites, but were less satisfied and perceived less sharing in the doctor-patient relationship compared with other ethnic groups. However, results suggest that data from standard functioning measures for Asians should be interpreted with caution and that more work is needed to understand better the social and cultural influences on the health of Asians and Pacific Islanders.