Morbidity and nutritional status of 200 children under 5 years of age, selected randomly from 19608families living in slum dwellings in the sity of Colombo have been related to their living conditions, per capita income of household and educational status of the mother. The incidence of diarrhoes was high in all age groups except during infancy, being very high where there was no toilet or a toilet was shared between several households, incedence of respiratory tract infections ranges from 33 to 48perc. being inversely related to the per capita floor area in dwelling. Angular stomatitis and glossitis were the main clinical manifestations of malnutrition, being highest in the 4-5 year group. The type of dwelling and the income of the household were the two most important factors determining the nutritional status at the children. The need for providing a hygienic and sanitory environment, clean drinking water and effective primary health care services, in addtion to poverty alleviation, is stressed.