We sought to determine whether the recent Centers for Disease Control recommendation of universal prenatal screening for hepatitis B surface antigen (HBsAg) is necessary or cost-effective in a population of private patients. During the 21 months of our study there were 17,973 deliveries at Magee-Womens Hospital, the largest-volume private obstetrics service in the United States. We screened 12,377 of these patients for HBsAg. Only 11 patients, 0.09% of those screened (5 private and 6 clinic) tested positive. We administered questionnaires regarding historical risk factors for hepatitis B to all 11 patients testing positive for HBsAg and to 100 controls who tested negative for HBsAg. All private patients and 5 of 6 clinic patients testing positive for HBsAg had identifiable risk factors for hepatitis B. In addition, historical risk factors for hepatitis B were identified in 29% of the women testing negative for HBsAg. We found historical risk factors to be excellent predictors of the presence of HBsAg in our private patients. Our data indicate that universal screening for HBsAg is not necessary in private patients.