The present study used data from a community-based epidemiological survey of 752 persons in 3 villages in Kisumu District, western Kenya, to examine the proportion of infected persons who would be treated, as well as the effect on helminth egg production, if anthelmintics were provided to schoolchildren. Overall prevalences of hookworm, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni infections were 63%, 16%, 24% and 24% respectively, and intensities were low for all infections. Only 79% of the school-aged children were enrolled. For all 4 infections, a school-based programme would treat between 76% and 86% of infected school-age children and would theoretically eliminate between 83% and 92% of the number of eggs excreted by this age group. Of the total population, school-based programmes would treat only between 31% and 50% of the infected persons and eliminate only 15%, 46%, 29% and 27% of the total number of hookworm, Ascaris, Trichuris and S. mansoni eggs excreted, respectively. Provided that school attendance rates were high in the study area, school-based programmes would be efficient in improving the helminth infection status of school-aged children. On the other hand, adults, non-enrolled school-aged children and preschool children not offered treatment represented more than half of the helminth-infected persons and they excreted between half and 85% of the total burden of helminth eggs in the area. Hence, mass chemotherapy of schoolchildren would be less effective in the control of at least hookworm and S. mansoni infections in this specific community. There should therefore be a community-based approach to helminth control in combination with a school-based programme.