This survey investigated the cesarean section rate in teaching hospitals in the United States and the factors that may influence it. A national survey was performed by mailing a questionnaire to 277 accredited residency programs in obstetrics and gynecology. The estimated cesarean rate in all hospitals with residencies in obstetrics and gynecology in the United States in 1990 was 20.3 percent, compared with an overall national rate of 23.5 percent. Women delivering in teaching hospitals were less likely to have a cesarean section than those delivering in hospitals without residency programs (odds ratio = 0.77, 95% CI 0.77-0.78, p = 0.0001). As centers for training and research, teaching hospitals represent an appropriate setting to begin the process of lowering the United States cesarean section rate.