This study was conducted to investigate the relationship between various socio-economic factors, and child morbidity and mortality during a period of rapid social change in Vietnam. One-thousand-one-hundred-and-thirty-two rural mothers with children under 5 years of age were interviewed regarding their reproductive history, survival of their children, and morbidity of their children under 5 years of age. Causes of child death were established by a verbal autopsy technique. Fifty-seven per cent of the children were reported to have suffered from some illness during the preceding 2 weeks. Acute respiratory infection (ARI) (46 per cent of all children) was most common. Two-thirds of the sick children had been treated with antibiotics. Eighty-one children under 5 years of age had died during the 10-year period 1982-1992. Two-thirds of these deaths occurred in infancy, most of them were related to prematurity, asphyxia or tetanus. ARI was more common in poor families while neither education nor occupation were associated with ARI occurrence. No significant relationship between education or occupation of the mother and mortality was found. The low under-5 mortality (U5MR) in spite of the high morbidity may be related to good child health care both by families and by the health care system.