To determine the level of professional satisfaction experienced by physicians practicing in Ontario, Canada, a probability sample of 1,028 physicians was surveyed; 69% responded. The majority of Ontario doctors were at least moderately satisfied with each of 16 aspects of their work, and the percentage who were dissatisfied exceeded 15% for only four aspects. Factor analysis suggested the presence of four underlying satisfaction facets: satisfaction with quality of care, with the rewards of practice, with patients, and with the practice environment. Multivariate regression analysis supported the validity of the four-facet model and demonstrated a consistent association between lower satisfaction and younger age, lower income, and the perception that it is difficult to obtain fair reimbursement for medical services (P less than 0.05). Least satisfied physicians were most likely to have participated in the June, 1986 Ontario doctors' strike (P less than 0.001). Despite some misgivings, the majority of physicians practicing under the Ontario Health Insurance Plan in 1987 were satisfied with their professional lives. They were least satisfied with their ability to make administrative decisions and to manipulate the system for the benefit of their patients. Policymakers should be cognizant of the effects various strategies may have upon physician satisfaction as they consider new approaches to health care organization.