Prevalence of malnutrition among under-five children is very high in many developing countries of the World. As a step towards reducing the prevalence, there is need to identify the important determinants of malnutrition in the specific context. This study examined the prevalence and determinants of malnutrition among under-five children of farming households in Kwara State, Nigeria. Descriptive and regression analyses were used to analyze anthropometrics data collected from 127 children selected randomly from 40 rural villages in the State. Descriptive results indicate that 23.6%, 22.0% and 14.2% of the sample children were stunted, underweight and wasted respectively. Regression analysis shows that the significant determinants of malnutrition were gender and age of child, education and body mass index of mother, calorie intake of the households, access to clean water and presence of toilet in the households. To reduce the present high rate of malnutrition in the area, the study suggests the targeting of women with education programmes and provision of clean water, including the enforcement of healthy environment in the rural areas.