PURPOSE. To determine whether an intensive conference series during a third-year medicine clerkship would produce a significant improvement in students' standard scores on the National Board of Medical Examiners (NBME) medicine subject examination when taken at the end of the clerkship and on the medicine section of the NBME Part II examination when taken during the fourth year. METHOD. A conference series of approximately 50 hours covering core topics of internal medicine was begun at the Oregon Health Sciences University School of Medicine in 1984–85. The series was repeated every 12 weeks, for each rotation of the third-year medicine clerkship. Standard scores on the NBME medicine subject examination taken at the end of the medicine clerkship and the medicine section of the NBME II taken in the fourth year were compared between the 173 students who participated in the conference series in 1984–85 and 1985–86 and the 466 students who took the clerkship from 1980–81 through 1983–84, before the conference series was implemented. The students' NBME II scores in surgery and pediatrics, the other disciplines that had 12-week clerkships but that did not implement curricular changes in 1984–85 and 1985–86, were also compared, as were the students' scores on the NBME I, which the students took prior to the medicine clerkship. RESULTS. The NBME I scores were not different between the two groups of students. The students who took the conference series had standard scores on the NBME medicine subject examination that were on average 49 points higher than the scores of those students who did not take the conference series. This difference was closely maintained on the medicine section of the NBME II, on which the group that took the series had a mean score that was 44 points higher. No improvement was seen in scores on the surgery and pediatrics sections of the NBME II. DISCUSSION. This retrospective review of students' performances on NBME medicine examinations taken at the end of the third-year medicine clerkship and as a component of the NBME II documents a substantial improvement in performance for students who took an intensive conference series as a part of the medicine clerkship curriculum. Further, the students' improved performance level carried over into the fourth year.