The authors attempted to measure the influence of a physical diagnosis course and its preceptors on the career decisions of second-year medical students. They designed pre- and post-course questionnaires for 204 second-year medical students in a University of Texas Health Science Center at San Antonio Advanced Physical Diagnosis course. They found that 48% of students changed their career choice during the study period, 75% believed their preceptor was a very good role model, and 39% thought their preceptor influenced their career choice. Students who believed their preceptor was a good role model were 31 times more likely to consider their preceptors' career (confidence interval [CI] 95, 4.1-236). In results from students precepted by primary care physicians, there was a nonsignificant trend toward choosing a primary care career (Odds Ratio [OR]) 1.6 [CI95, 0.7-3.3]). Factors associated with a final career choice of primary care were a primary care career choice at baseline (OR 8.5 [CI95, 3.8-19.0]) and a belief that physical diagnosis skills would be important to a future career (OR 4.7 [CI95, 1.1-20.0]). By multivariable analysis, only a primary care career choice at baseline remained significant (OR 8.7 [CI95, 3.5-21.3]). The authors concluded that good role models can influence students to consider alternative career choices, but this effect is still overshadowed by a student's baseline career choice.(ABSTRACT TRUNCATED AT 250 WORDS)