In malaria endemic forested villages in Orissa State, India, a 3-year comparison of nylon nets treated with lambdacyhalothrin at 25 mg/m2, untreated nets, and no nets was carried out. Treated nets retained high insecticidal efficacy for more than 7 months. Nets washed after 3 months of use gave 98% kill in a bioassay with a 3-min exposure. Based on these bioassays during the first year, nets were later reimpregnated at 6-monthly intervals with participation of the users. Compliance with the use of nets was good. Eighty-eight percent of nets were usable even after 3 years. The main benefits perceived by treated net users were reductions in malaria, mosquito bites, head louse infestations, and other nuisance insects. The trial was well accepted by the community. Issues related to social marketing and promotion of nets are discussed.