Village-wide use of permethrin-impregnated bed nets, compared with placebo-treated nets, has reduced clinical attacks of malaria by 63% in the Gambia. Costs were calculated for nets made by local tailors and for their treatment with insecticide in the villages, as well as for targeted chemoprophylaxis and back-up treatment for fever, in a comprehensive malaria control strategy through primary health care. The villagers' preferences for bed net fabrics and willingness to pay for them, and their preferences for various items of expenditure by ranked order, age group, and sex are given. Ethnic differences in the use of bed nets are also discussed.