Abstract: Malnutrition among preschool children is an indicator of underdevelopment and is high in many developing communities. Malnutrition affects performance of children in the later adulthood life. Though determinants of malnutrition vary from region to region, the underlying cause for malnutrition is poverty. A cross-sectional study was conducted to identify prevalence and determinants of nutrition status of preschool children in the Rift Valley in Kenya. Mothers of these children were respondents who provided information on selected variables. Nutrition status was measured by weight-for-age, height-for-age and weight-for-height. General prevalence of malnutrition was still high in this population, with more males than females having poor nutrition status as measured by weight-for-age, height-for-age and weight-for-height. Risk factors for malnutrition in this population were age, sex, education level of the head of household, time taken by women on other household chores (especially collecting fuel wood), number of pregnancies a mother has had, income of the head of household and income from cash crop farming. Education level of household heads could improve nutrition through appreciating the role of good nutrition for child development and availing resources at the household level for adequate nutrition and health. The major determinants of malnutrition included time spent on household chores (30%), income (12%) and gender (10%).