Children born to mentally retarded mothers usually have normal intelligence. Their fathers often suffer from psychosocial problems. These children often grow up in an environment of insecurity and understimulation. How many are there? In 1995 an inventory was made in Skaraborg county (275,000 inhabitants), Sweden, based on the mothers' registration with the county authorities responsible for supporting people with mental retardation and on the general population register. A prevalence of 1.4 per thousand was found. Reasons for a higher true prevalence are discussed. The majority of the mothers had mild mental retardation. The rate of childbearing among mentally retarded women fell from 30 to 15 percent over the last three decades up to 1995. The prevalence for women with mental retardation was at least 1.1 percent.