METHODS National Masan Tuberculosis Hospital, Korea. OBJECTIVE Treatment for multidrug-resistant tuberculosis (MDR-TB) is considered to be clinically important, but there are few reports on this topic. We therefore retrospectively evaluated the outcomes of chemotherapy only for pulmonary MDR-TB. METHODS We reviewed the clinical courses of 107 patients with pulmonary disease due to Mycobacterium tuberculosis resistant to rifampin and isoniazid who were under follow-up between March 1996 and June 1996 after hospitalization between January 1993 and January 1996. We performed a retrospective cohort study for all the patients' records. Their regimens were selected individually and preferably included four medications that they had not been given previously and to which the strain was fully susceptible. RESULTS The 107 patients (mean age 38.3 years) had previously received a mean of five drugs, and were shedding bacilli that were resistant to a mean of four drugs. Of 63 patients with sufficient follow-up data, 52 (82.5%) responded to chemotherapy (as indicated by negative sputum cultures for at least three consecutive months); 11 (17.5%) had no response, as shown by continually positive cultures. In a univariate analysis, an unfavorable response was significantly associated with resistance to a greater number of drugs before the current courses of treatment (relative risk 21.5; 95% confidence interval 1.2-3.0; P < 0.05). The mean period of follow-up was 17 months. There was no subsequent relapse among the patients with responses, and there were no tuberculosis-related deaths. CONCLUSIONS In this study, multidrug-resistant pulmonary tuberculosis responded relatively well to carefully selected regimens.