In the last decade the teaching of medical ethics has become almost universal in American medical schools. Its effectiveness is, however, just beginning to be evaluated. A stratified random sample of 3,000 practicing physicians who were graduated between 1974 and 1978 was surveyed to evaluate their perceptions of the utility and relevance of medical ethics teaching. Those who had courses in medical ethics perceived it to be of substantial benefit in confronting the actual ethical issues they encountered in daily practice. They favored the continuation and expansion of the teaching of medical ethics and had suggestions for its improvement. Data were also obtained on the relative frequency of specific ethical issues in practices and on the relative influence of home, personal values, medical education, medical practice, and ethics courses on respondents' approaches to ethical issues. (JAMA1985;253:49-53)