Insecticide-treated bed nets (ITNs) have been demonstrated to reduce morbidity and mortality in children less than five years of age. They have also been shown to improve the nutritional status of these children, but little is known about their impact on the nutritional status of school-age children. We evaluated the impact of ITNs on growth, nutritional status, and body composition of primary schoolchildren less than 13 years of age living in an area of intense perennial malaria transmission in western Kenya. The ITNs did not have a significant impact on linear growth or summary measures of protein-energy malnutrition in this age group. This lack of efficacy most likely relates to the reduced burden of malaria in this age group in a setting of stable transmission pressure. Use of ITNs was associated with a change in body composition with an increase in percent lean body mass (1.2%; P = 0.04). This may be consequent to reduced exposure to malaria with subsequent reduced elaboration of pro-inflammatory cytokines known to promote muscle wasting.