This paper was carried out to study on correlation between mentally retardation and lead and zinc. The subjects were 297 mentally retarded children: 132 of Bomyung special school and Sunmyung, which were located in Taegu city of Korea. The former had their parents but the latter had not. The control group 63 children were randomly seleted from the Dong-in primary school near to Medical School of Kyungpook National University. Atomic absorption spectrophotometer, model IL-551 connected with CTF atomizer(IL. 655) was used for the analysis of lead and zinc. The mean value of lead in hair of mentally retarded children was 14.97 3.71ppm which is significantly higher than that of control group, 11.36 2.83ppm. But the content of zinc was not significant in both groups. In the lead there was no significant correlation to age but significant negative correlation to IQ. Zinc showed significant correlation to age but not to IQ. Among the handicapped children, no signigicant correlation between orphan group and non orphan group. Handicaps of mentally-retarded children were speech impairment, emotional disturbance, double and triple handicaps, sensory impairment and abnormal dietary patterns. There were significantly higher contents of lead compared with normal group, except the latter two groups. The disease conditions of mentally retarded children were mongolism, autism, cerebral palsy, epilepsy and microcephaly. In comparing with mongolism, significant difference were existent only on the cerebral palsy and group of unknown etiology. We attempted to divide their past history into external etiology and internal etiology, but could not find significant difference. In view of the whole results, the relationship between mentally-retarded children and lead was presumed to be the early time exposure rather than long interval exposure during growth and the contact opportunity was considered important subject in maternal and child health care.