RESUMO
Medical records of children who attended the Genetics Unit of Ain Shams University Hospital in the period between January 1982 and December 1989 were reviewed. These comprised 1607 cases of mental retardation, 904 males and 703 females whose ages ranged from 1 to 12 years. Their intelligence quotients from less than 20 to less than 70. Considering the onset of mental retardation, the percentage of mentally retarded due to prenatal causes, prenatal causes and postnatal causes were 32.6%, 18.2% and 26.3% respectively, while 22.7% had undecided causes. Regarding the level of mental retardation, 17.7% of the cases had profound mental retardation, 37% had severe, 27.3% had moderate mental retardation and 18% were midly mentally retarded. The importance of complete history taking, thorough clinical examination besides properly selected investigations in diagnosis of children with mental retardation is emphasized