Physicians are increasingly practicing within structured or organized practice settings, even though it is frequently assumed that such organizations are inherently dissatisfying to physicians. In this study, a sensitive measure of physician satisfaction is used to compare physicians working in four types of practice settings: private group practice, solo practice, a closed-panel health maintenance organization (HMO), and a hospital-based practice.A questionnaire was mailed to all physicians in a four county area in western Massachusetts, from which 1302 practicing physicians were identified. Based on responses to the questionnaire, the physicians were placed into one of the four practice arrangements. Satisfaction was measured by using an index methodology, with six statistically acceptable measures of satisfaction.All physicians surveyed were most satisfied with the personal and lifestyle factors related to their practice, regardless of practice setting. Those in a private group practice were the most satisfied. However, physicians in an HMO setting were more satisfied with medicine as a profession and less dissatisfied with the state's medical practice climate than physicians in the other practice settings. It appears that HMOs provide professional satisfaction by buffering physicians from the external regulatory climate, permitting them to focus more on patient care.Identifying the factors that cause physician satisfaction and dissatisfaction within the various types of practice settings becomes increasingly important as current health care reform efforts continue to promote more structured practice environments. More research is needed to identify the various organizations physicians are involved with so that physicians' professional level of satisfaction can be maximized.