Early reports on the quality and duration of marriages that involve adults with mental retardation have documented both problems and possibilities.1-5 Today, adults with mental retardation are marrying and having children, and adult unmarried women with mental retardation (even moderate to severe mental retardation) are having children. The true prevalence of parents with severe intellectual limitation is unknown and possibly unknowable. An accurate differential diagnosis of the cause of cognitive deficiency in an adult who is living in the community is difficult to obtain in the absence of records of formal childhood testing. Nevertheless, in a key informer survey performed in the city of St Louis, Mo, the number of children of mentally retarded mothers, who were identified, suggested that adults with mental retardation were having children on the same order of magnitude as the rate in the general population, with a mean number of 2.8 children per retarded