Efficacy of two 4.5-month regimens (3 RSZH / S2H2Z2 and 3 RSZH /RH) and one 3-month regimen (3 RSZH ) in the management of pulmonary tuberculosis is reported (see table 1 for definition of regimen abbreviations). Even when the patients were ambulatory and outpatient attendance was required for supervised drug administration, drug compliance was high (87%). Bacillary sterilization was achieved in 99% of the patients at 3 months. During first year follow-up after cessation of chemotherapy, 6% of the patients receiving the 3 RSZH regimen, 7% of the patients receiving the 3 RSZH / S2H2Z2 regimen, and 2% of the patients receiving the 3 RSZH / R2H2 regimen experienced relapse. During second year follow-up, relapse was observed in only 1 patient receiving the 3 RSZH / S2H2Z2 regimen. The patients who relapsed usually had drug-susceptible strains at the time of relapse. Regression of pulmonary lesions continued even after the cessation of chemotherapy.