Eighty-seven patients with multidrug-resistant tuberculosis (MDR-TB) diagnosed between 1988 and 1990 were treated with isoniazid and at least three other effective second-line drugs based on in vitro susceptibility tests. Of these patients, 10% failed to adhere to the regimen and 43% remained sputum positive after 6 months of treatment. Only 47% showed sputum conversion within 6 months of treatment and 12% of them relapsed during the first year of follow-up. From September 1987 to July 1989, 36 patients with MDR-TB were treated with a regimen containing rifabutin, isoniazid and at least three other susceptible drugs. Only 47% achieved a sustained sputum conversion. Four died during treatment due to disease progression. From March 1992 to July 1993, 17 cases of MDR-TB were treated with an ofloxacin-containing anti-TB regimen for 12-24 months. Two failed to adhere to the regimen for more than 1 month during the first 6 months of therapy. Among the remaining 15, 26% failed to achieve sputum conversion, 73% achieved bacterial conversion, 9 within 1 month and the other 2 within 2 months. No significant adverse effect was associated with ofloxacin use. We concluded that ofloxacin is a better choice among the more toxic and less potent second-line drugs, and should be used along with other anti-TB drugs in treating patients with MDR-TB.