The attitudes of third-year medical students toward cancer and patients with cancer was examined before and after a 6-week clerkship that included contact with pediatric patients with cancer and their families. A 51-item testing instrument was employed, which included pediatric, adult, and general oncology questions. Beginning with positive attitudes toward the importance of early diagnosis, aggressive therapy, and the complete disclosure of prognosis, the clinical exposure appeared to strengthen the two former attitudes and somewhat diminish the latter. Approval of aggressive cancer therapy was stronger for children than for adults; but approval of both aggressive therapy and intensive surveillance of patients in remission was increased in regard to adults as well as children after the clerkship. A comparison with responses of second-year medical students from another institution suggests that third-year students recognize greater personal limitations in respect to management and adopt a more "defensive" position regarding the patient. In general, during the clerkship, the students moved in the direction of attitudes that were previously designated to be appropriate for students by a multidisciplinary committee that was distinct from the instructional staff in oncology.