PURPOSE: Initial drug resistance of children with tuberculosis is a useful performance indicator of tuberculosis control programme in the concerned country because it represented infection transmitted from adult patients with either primary or acquired drug resistance. But there have been a few studies available. The present study was made to know the incidence of drug-resistant tuberculosis in hopes of selecting effective treatment regimens for the treatment of childhood tuberculosis. METHODS: Tuberculosis patients were selected from those whose cultures had been submitted to drug susceptibility testing in the Korean National Tuberculosis Association from Jan. 1987 to Jun. 1995. We have investigated the drug resistance and reviewed retrospectively the medical records of children. A total of 48 strains were tested for drug susceptibility. Of these cases medical records were available in one half and 22 patients did not have a history of previous antituberculosis therapy. RESULTS: 1) Of the 48 strains, 18 (37.5%) were resistant to 1 or more antituberculosis drugs. The 14 (29.2%) and 8 (16.7%) strains were resistant to isoniazid and rifampin, respectively. The 7 (14.6%) strains were resistant to both isoniazid and rifampin. 2) Of the 22 strains isolated from patients without previous therapy, 4 (18.2%) were resistant to 1 or more antituberculosis drugs. The 2 (9.1%) strains were resistant to isoniazid. There were no resistant strains to rifampin and to both isoniazid and rifampin. CONCLUSIONS: Primary resistance rate for isoniazid was 9.1%. These limited data suggested that four-drug regimens is indicated in childhood tuberculosis patients.