Methods: Prospective, comparative, randomized and open trial of patients with positive TST and the suitable criteria for treatment, in accordance with the guidelines of the CDC, excluding HIV infection. the group I was assigned to isoniazid (H) at a dose of 300 mg per day for 6 months and the group II was assigned to isoniazid at a dose of 300 mg per day plus rifampin (R) (600 mg per day) for 3 months. The patients were followed for five years.