Some socio-economic and demographic factors contributing to nutritional status (underweight and wasting) of children aged 1 to 4 years (n = 949) were studied in selected low income urban areas in Tanzania. Children were classified as either normal or malnourished and logistic regression was used in the analysis. Of the demographic variables studied, sex of the child was significant using both weight-for-age and weight-for-height indices. Males had better nutritional status than females. Mother's education level and age were significant risk factors using weight-for-age. Immunization status of the child and household density were also significant, but their effects became insignificant when morbidity and dietary variables were included in the analysis. Using weight-for-height the place of residence and number of children under 5 years in a household had significant effects on nutritional status through the latter was less significant when morbidity variables were incorporated. Children from big towns were significantly better off nutritionally than those from small towns. For dietary and morbidity variables frequency of feeding and diarrhoea were significant predictors of nutritional status (weight-for-age) while malaria was a significant predictor of weight-for-height.