Depression is underdiagnosed and undertreated by nonpsychiatric practitioners. Research suggests improvement is needed in the recognition and treatment of depressive disorders by primary care physicians. This study was undertaken to better understand internists' ability to recognize depressive disorders, choice of appropriate medications, dosage, and treatment patterns. Questionnaires were distributed to 45 internal medicine attendings, 45 internal medicine housestaff, and 32 adult psychiatry residents. Each questionnaire contained four vignettes: major depressive disorder (MDD), MDD with melancholic features, MDD with atypical features, and MDD with psychotic features. Eleven questions per case covered diagnoses, management, and treatment. Data analysis with intragroup comparisons on 20 internal medicine attendings, 33 internal medicine housestaff, and 32 psychiatry residents suggested that many internal medicine attendings and housestaff had difficulty in recognizing major depression and its subtypes. Although the findings indicated that internists would initiate pharmacological treatment, they frequently made incorrect or questionable pharmacological choices. Psychiatric referral or consultation was often endorsed. Our findings among internists are consistent with previous research examining other primary care physicians suggesting that depression is underdiagnosed and undertreated.