The authors describe research in undergraduate medical education as reported in journal articles. A sample of 773 articles was randomly selected from 3,689 articles published from 1975 through 1994. Content analysis was used to quantitatively assess subject interests and methods over the past 20 years. The most frequent topics related to curriculum, teaching, and student assessment. Over 45% (353) of the sample articles were reports of research activity (i.e., they used specific methods to ascertain new facts, concepts, or ideas). The research reported was overwhelmingly conducted in a naturalistic environment; was evaluative or comparative in design; used observation, testing, or questionnaires to collect data; and included inferential statistical analyses. The research described by the authors confirms the close relationship between medical education and clinical or laboratory environments. The literature on undergraduate medical education reflects a lack of theory-based research and little evidence of work built on prior research, which may be partially due to the scattered nature of the literature. The increased numbers of authors per article over the study period may be indicative of increased interdisciplinary collaboration. The lack of reported external funding may be a problem of underreporting or it may be related to the large number of single-institution-based studies.