As part of the Federal/Provincial/Territorial Review on Liability and Compensation Issues in Health Care, in 1988 we surveyed Canadian general practitioners and family physicians to determine the effect of liability concerns on their practices in the previous 5 years. Questionnaires were sent to a random, stratified national sample of 1295 physicians, with a response rate of 64.6%. However, a high proportion of the returned questionnaires were ineligible because the physicians were not in general or family practice, were not involved in direct patient care, or had died or moved; thus, the corrected response rate was 50.8%. The newsletter of the Canadian Medical Protective Association was the source of information on liability most frequently cited (by 88.1% of the physicians) and most influential (to 62.4%). Only 15.5% of the physicians cited personal involvement with medicolegal issues as a source of information; the rate was higher for Ontario physicians and those in urban areas generally. A total of 74.6% of the respondents had altered their style of practice in the previous 5 years, and 56.3% reported changes in the scope of their practice. Concern about litigation was the most important reason for changing style of practice and reducing or eliminating administration of anesthesia, whereas lifestyle and other issues along with liability concerns most influenced decisions to reduce obstetric care and emergency department work. Our findings suggest that physicians' perceptions of liability issues have had a profound influence on primary care practice in Canada in the past several years.