Some 5-15% of children aged 3 to 15 years in both developing and developed countries suffer from mental handicaps. There may be as many as 10-30 million severely and about 60-80 million mildly or moderately mentally retarded children in the world. The conditions causing mental handicaps are largely preventable through primary health care measures in developing countries. Birth asphyxia and birth trauma are the leading causes of mental handicaps in developing countries where over 1.2 million newborns die each year from moderate or severe asphyxia and an equal number survive with severe morbidity due to brain damage. The other preventable or manageable conditions are: infections such as tuberculous and pyogenic meningitides and encephalopathies associated with measles and whooping cough; severe malnutrition in infancy; hyperbilirubinaemia in the newborn; iodine deficiency; and iron deficiency anaemia in infancy and early childhood. In addition, recent demographic and socioeconomic changes and an increase in the number of working mothers tend to deprive both infants and young children of stimulation for normal development. To improve this situation, the primary health care approach involving families and communities and instilling the spirit of self-care and self-help is indispensable. Mothers and other family members, traditional birth attendants, community health workers, as well as nurse midwives and physicians should be involved in prevention and intervention activities, for which they should be trained and given knowledge and skills about appropriate technologies such as the risk approach, home-based maternal record, partograph, mobilogram (kick count), home-risk card, icterometer, and mouth-to-mask or bag and mask resuscitation of the newborn. Most of these have been field-tested by WHO and can be used in the home, the health centre or day care centres to detect and prevent the above-mentioned conditions which can cause mental handicap.