The purpose of the study presented here was to assess medical students' perceptions of the weight given to scientific and humanistic values in their learning environment and to determine whether students' perceptions in a given school vary according to their level of medical training and personal characteristics. The study was conducted in 1979 via a mail questionnaire sent to a sample of 713 freshmen, juniors, and graduates from three U.S. medical schools; 82.2 percent responded. The results indicated that the students' perceptions of school values varied little according to the students' personal characteristics, such as sociodemographic and educational background, interests before medical training, and expected specialty choice. However, important differences were observed in students' perceptions of values emphasized to them at different schools. Preclinical and clinical students' perceptions of the importance given to scientific values were similar. As for humanistic values, significantly lower ratings were given by clinical students than preclinical students in two of the schools.