A family is described in which an asymptomatic woman gave birth to a male child with complete congenital heart block. Precipitating antibodies to the Ro/SSA antigen have developed in this child, now aged 33, who is clinically well. In the mother, features of both systemic lupus erythematosus and Sjögren's syndrome developed 26 years after the birth of her son. Her serum currently has precipitating antibodies to both the Ro/SSA and La/SSB antigens. The presence of anti-Ro/SSA in the child with complete congenital heart block and the extremely long delay of 26 years between the delivery of the child and the development of clinical disease in the mother are discussed in light of investigators' developing knowledge of both neonatal and adult systemic lupus erythematosus.