SummaryRubella antibody was detected in 85 (61%) of 139 children aged from 6 months to 7 years with congenital perceptive deafness. Of the 112 children who were aged under 4 years 61 (54%) had rubella antibody (seropositive) compared with 7-1% in randomly selected children of the same age. A close correlation was found between the presence of antibody in children with perceptive deafness and (1) a maternal history of rash or contact in early pregnancy, and (2) with the presence of other rubella-type defects. Intrauterine rubella was thought to be the cause of the deafness in 82 (59%) of the 139 children, in 60 of whom deafness was the only rubella defect detected. Thus intrauterine rubella should be considered a likely cause of congenital perceptive deafness in a child under 4 years in whom rubella antibody is present.