People infected by Trichuris trichiura were selected in a community by the Kato-Katz technique. The study included a universe of 376 persons, male and female, positive and asymptomatic, monoparasitic and multiparasitic. They were divided in treatment groups with not less than 50 people. Monoparasitic patients were treated with 500, 400 and 300 mg of mebendazole, and multiparasitic patients with 500 and 400 mg of mebendazole. In all the cases the drug was used in single doses and its administration was supervised by the physician. Therapeutical response in monoparasitic and multiparasitic patients is shown. It is suggested to use mebendazole single doses of 300 mg in monoparasitic and of 400 mg in multiparasitic patients with an intensiveness of less than 5,000 h/g, as an alternative for treating asymptomatic populations with T. trichiura.