This study assessed the nutritional status using anthropometry of 1-4 year old children in an urban slum in the Mushin Local Government Area of Lagos State, with a view to determining the impact of urbanization on child health. A total of 365 children were enrolled using multistage random sampling techniques. Anthropometric measurements used were weight and height. Height-for-age, weight-for-height, and weight-for-age Z-scores below -2.00 SD of the reference NCHS standard were used to define stunting, wasting and underweight, respectively. The study revealed a prevalence of underweight of 39.2%, stunting of 34.5% and wasting of 21.9%. The mean of weight-for-age, height-for-age, weight-for-height and mid-upper-arm-circumference were less than the mean of the NCHS reference population. This difference might be due to the socio economic backgrounds of the two populations. Using the modified Wellcome Classification of malnutrition, 37.8% of the children were malnourished. Most subjects came from homes with inadequate water supply and poor refuse disposal methods.