New adult patients (n = 212) were randomly assigned to 58 primary care resident physicians. Physician practice styles during initial and return visits were analyzed using the Davis Observation Code. Compared with initial patient visits, return visits were shorter, but more work-intensive. Return visits displayed significantly less technically oriented behavior (including history taking, physical examination, and treatment planning) and fewer discussions regarding use of addictive substances; however, there was more emphasis on health behaviors and active involvement of patients in their own care. These physicians' practice style differences between initial and return patient visits suggest that physician-patient familiarity affects what happens during the medical interview.