Beginning with the class graduating June 1984, Dartmouth Medical School introduced a required clinical pharmacology course. Approximately 89% of the fourth-year students felt that the course was "essential" to their future careers as physician. As interns, 80% found the course frequently useful or essential during their internships; 84% felt that they were either slightly or much better prepared than their fellow interns with respect to their therapeutic knowledge and skills. Average student performance on a pretest (33% correct answers) improved dramatically on a posttest (87% correct; P < 0.001). Finally, although student performance on all sections of Part II of the national broad examinations showed statistically nonsignificant trends toward improvement (from the 48th to the 52nd percentile), performance on questions testing core concepts in clinical pharmacology improved from the 38th percentile to the 74th percentile (P < 0.0001). This required fourth-year course in clinical pharmacology was evaluated favourably by our students and resulted in objective improvement in their therapeutic knowledge and skills.