To better understand the medical internship, a required and critical part of the educational preparation of young physicians, and its relevance for their future careers, the experience of interns on the Harvard Medical Service at the Boston City Hospital was documented. The principal method used to gather information was participation in and observation of the daily activities of an internship, in the clinics, wards, meetings and lectures. During the 18-month investigation, hypotheses were formulated and tested by further observation and direct questioning. To compare the experience of Harvard interns with the internship program at another hospital, 3 months were spent as a participant/observer at a community hospital. An objective test, a questionnaire and the National Board of Medical Examiners examination were also evaluated. Although most interns aspired to careers in teaching or research, they and advisors agree that a straight medical internship should be served, preferably at a university-affiliated hospital. There, because of heavy demands, their work consists almost entirely of attending patients. To reconcile directing their efforts toward patient care rather than formal academic learning, interns justify their work as an educationally beneficial clinical experience. They thus reduce the conflict between their own academic desires and the hospital's purpose. "Learning the ropes" is a crucial factor in an intern's success. Although the work of the internship at the university and the community hospital was similar, the programs differed because of conditions and objectives. (JS)