Between January 1, 1986 and July 1, 1988, 56 cases of congenital syphilis were identified at the University of Miami/Jackson Memorial Medical Center. The overall rate was 18.4 cases per 10,000 births, with a threefold increase found from 1986 to 1988. A case-control study using matched pairs was done to identify differences in maternal demographics and pregnancy outcome. Congenital syphilis case mothers were predominantly black American women who lacked prenatal care (67%) and who were substance abusers (71%) significantly more often than their matched controls (P less than .005). Three cases of seroconversion in pregnancy were identified. Failure to screen or inappropriate treatment occurred in four patients. Seven women were treated during pregnancy: Five received benzathine penicillin G for 3 consecutive weeks and two received erythromycin. All treated patients presented for initial care in the late second or third trimester. Thirty-seven infants (66%) were live-born and 19 (34%) were stillborn. Preterm labor and premature rupture of the membranes were significantly more common in infected pregnancies than in controls (P less than .005). Live-born case infants had significantly lower birth weights than controls (P less than .005), with 21% of case infants growth-retarded. Seven neonatal deaths and one infant death occurred. The resultant perinatal mortality rate from congenital syphilis in this series was 464 pe 1000.