A study was conducted in an urban slum area of Kuala Lumpur, the capital of Malaysia, to determine the health status of the children under 6 years old and the knowledge and practice associated with diarrhoeal diseases and use of oral rehydration salts (ORS) among mothers in the area. It was seen that the health status of the children was poor with one fifth of them born underweight, 33% experiencing more than 6 spells of illness per year and a high percentage of them suffering from diarrhoeal diseases (4.3%). Child care practice was associated with urban lifestyles with early weaning, short term breast-feeding and early introduction of solid and bottle feeding. Knowledge and practice of mothers concerning child care was inadequate to support healthy living. Knowledge of diarrhoeal diseases and the effectivenss of oral rehydration salts was poor. Only 47.7% of mothers knew about ORS and 27.8% ever used it when their chidlren suffered from diarrhoea. Health care system dependence was shown by the high percentage of mothers immediately bringing to a doctor's attention (75.6%).