Objectives: To evaluate clinical, laboratorial, epidemiological, and therapeutic aspects of patients presenting with multiresistant tuberculosis (MRTB). Patients and methods: From January 1993 to December 1994, a prospective, non-randomized study of patients presenting MRTB, characterized by failures under treatment schemes E-1 and E-3 according to the classification of the Brazilian Ministry of Health, and resistance to isoniazid and rifampicin was carried out. Clinical and laboratorial aspects were considered: age, gender, ethnical group, duration of condition, cavity occurrences in conventional X-rays, resistance to drugs by the indirect method according to Canetti's et al. proportional criteria; epidemiological aspects such as risk predictor factors for multiresistance and treatment results. This study consisted in two alternative chemotherapy courses combining an aminoglycoside, amikacin (Group A), or S, if sensitive (Group B), ofloxacin, clofazimine, in addition to other drugs, such as thiacetazone, ethambutol, or pyrazinamide, according to the sensitivity or to the prior limited use for a minimum of twelve months. Patients with unilateral radiologic lesions, functional possibilities, and who have accepted the indication were submitted to surgery (Group C). Treatment was at the outpatient clinic, self-administered, or under indirect supervision, with hospital admission allowed for clinical reasons, for a limited time, or when surgery was indicated. Patients with prior alternative treatment, those infected with HIV, pregnant patients, and those with renal failure were excluded from the study. Evaluation extended to twelve months after completion of treatment. Results: 70 patients with mean age of 37 years, 42 male, 44 caucasian, and 26 non-caucasian (two orientals), average duration of the condition of four years, and bilateral cavitary lesions in 55 (78.6%). Resistance to two drugs in 28.6%, 51.4% to three drugs, and 20% to four drugs. The most frequent risk predictor factor for MRTB was abandonment (54.3%) followed by recurrence after cure with treatment scheme E1 and failure at retreatment (14.3%), intolerance to drugs (11.4%), contact with MRTB (8.6%). The risk predictor factor could not be determined in 11%, acquired multiresistance being considered in 80%, and primary multiresistance in only 8.6% of the patients. Cure was observed in 25 patients of Group A (n = 39), 11 patients of Group B (n = 24), and 3 of Group C (n = 7). Only two discontinued treatment (A) and only two died during treatment (C). In the control period, three patients had recurrences (1 in A, and 2 in B), and 7 died (3 in A, 2 in B, and 2 in C). The effectiveness of Group A was 67.6% (25/37) at completion of treatment, and 64.9% during the post-treatment control. The effectiveness of Group B was 45.8% (11/24) at completion of treatment, and 37.5% during the post-treatment control. The effectiveness of Group C was 42.8% (3/7) at completion of treatment and during the post-treatment control. After twelve months, effectiveness at treatment completion in Group A fell from 64.1% to 61.5%, in Group B, it fell from 45.8% to 37.5%, and it remained unchanged in 42.8% in Group C, where the four cases of failure died. Drug discontinuation due to adverse effects occurred late in two cases, and other adverse effects were noted, but did not foster discontinuation of treatment.