Background: PCEs are hypothesized to increase affinity for primary care careers. Subjects: Four focus groups (FGs) of randomly chosen medical students stratified by gender and year of medical school ( 40 students invited, 30 attended). Approximately 150 year I medical students surveyed by questionnaire. Design: Students were surveyed before and after year I (average response rate, 92%). FGs assessed year I students after the PCE and year 2 students without a PCE (controls). This pilot PCE included 14 half-days of "shadowing'' an office-based generalist during first semester. Analysis: FG transcripts were coded using a published model of career choice in Internal Medicine. Results: Among many positive comments (e.g., "wonderful role models", "'got me fired up about med school"), some unexpected themes emerged, including discomfort with patient relationships ("direct patient contact was intimidating and a “tum off"), boredom ("Internal Medicine ... got repetitious", "peds was boring ... so many well-child exams") and primary care backlash ("too much push to primary care'). Learning climate comments were often negative in controls but less so in PCE students. When compared with men, women cared more about role conflict (work/home) issues, and made more positive comments about intellectual stimulation of the PCE. Survey results showed no change in interest in a primary care career after the PCE (44% interested before vs 46% after, P = 0.09). Conclusions: A PCE can have positive and negative influences on career choice. These influences may differ by gender. Students could gain a greater affinity for generalism by better preparation for interacting with patients, careful selection of preceptors, and less pressure to enter primary care.