Clinical patterns, aetiological factors and utilization of services were studied in 40 families who had more than one handicapped child. By retrospective review of the case notes and interviewing consenting parents (90%), data relating to diagnosis, investigations, genetic counselling, social circumstances and help received were obtained. Both children had the same disorder in 31 families, however in only nine of these families did the children have a specific diagnosis. Non-specific mental retardation was the commonest disorder (40 children). Of the 673 special investigations performed, only 14 were diagnostic. Genetic counselling had been given to only 19 families. Thirty-two of the families had remained as stable units and of the children, 51 received attendance allowances and 21 had periods of respite care. The implications of these findings are discussed.