Fourth-year medical students at the four training sites of the University of Illinois College of Medicine were surveyed as to the frequency and difficulty of 99 interpersonal conflict situations that had been identified by their peers, supervisors, and coworkers. The situations were classified by the authors into two types, those requiring assertiveness skills and those requiring aggressiveness skills. A majority of the conflict situations involved students interacting with authorities (mostly residents and attending physicians), and three-quarters were of the aggressive type. The students reported the least difficulty with assertive-type conflict situations that involved peers and with aggressive-type conflict situations that involved nurses. Students at the Chicago campus reported more problems than those at the smaller, regional sites. The only significant difference between men and women students was that the women reported more occurrences than the men of aggressive-type conflict situations involving nurses.