The objectives of this study are to assess the incidence of congenital complete heart block (CCHB) in pregnant women who are anti-Ro and/or La positive. Between January, 1988 and July 1997, 118 pregnancies in 105 women were assessed by fetal echo at 18, 24, and 32 weeks' gestation. Of these 105, 96 had no history of a previous fetus with CCHB; 11(12 pregnancies) a history of a pregnancy with CCHB; and 4 a previous child with cutaneous neonatal lupus erythematosus (CNLE). The 102 pregnancies in 96 women with anti-Ro and/or anti-La antibodies and no history of a previous child with NLB, resulted in 100 live-births with no CCHB. There was 1 dilated cardiomyopathy at 6 months, 1 child with CCHB, and 1 with sclerosis of the endocardium. No case of CCHB was observed in 102 pregnancies without a previous history of CCHB. These results suggest that the risks of CCHB, without a prior history are low.