We used information from the Group Health Cooperative of Puget Sound, Washington, USA, to evaluate the risk of birth defects in mothers exposed to topical tretinoin--a retinoid preparation used to treat acne--in the first trimester of pregnancy. We identified 215 women who delivered live or stillborn infants at Group Health Cooperative hospitals and who were exposed to topical tretinoin early in pregnancy, and 430 age-matched nonexposed women who delivered live or stillborn infants at the same hospitals. The prevalence of major anomalies among babies born to the exposed women was 1.9% and among babies born to the nonexposed women was 2.6%. The relative risk estimate for having a baby with a major congenital anomaly for exposed versus nonexposed women was 0.7 (95% CI 0.2-2.3). We conclude that topical tretinoin is not associated with an increased risk for major congenital disorders.