A baseline cross-sectional study was done to evaluate the nutritional status of the population of the Mohale Dam catchment area before construction of the dam commenced. In this article we report on the anthropometric, clinical and dietary assessment of the children less than 15 years of age in the study population. A two stage stratified sampling technique was used to randomly select 29 of the 83 villages in the study area. Children under 15 years of age from 395 households, representing approximately 50% of households in the selected villages, were included in the study. Anthropometric measurements of body height and weight in relation to age and sex indicated undernutrition varying, with few exceptions, from high to very high levels in children under 15 years. Stunting, indicating chronic undernutrition, was of particular concern in children, even from the first year of life. Very few clinical signs of nutritional deficiencies were found except for a goitre prevalence of 17.5% in 10 to 14 year old children. This was supported by the very low urinary iodine excretion (median 1.3 micrograms/dL) which indicated a severe iodine deficiency. Dietary evaluation showed high initiation rates of breastfeeding as well as a long duration of breastfeeding. Complementary foods were introduced at an early age, resulting in low exclusive breastfeeding rates. Regular meals were reported but qualitative analysis of the diet showed that a too small variety of foods were eaten, with an irregular intake of protein-rich foods and milk. Quantitative data on 3- < 5-year-old children showed that micro-nutrient intakes were low and that the energy intake of these children was inadequate. The results showed that these nutritionally vulnerable children should be monitored for the impact of the dam construction on their nutritional status.