BACKGROUND: The anti-mycobacterial susceptibility test is performed on only a small percentage of clinical isolates in Korea. The aim of this study is to propose an anti-mycobacterial susceptibility testing scheme, which is not only economic and practical but also fully informative to physicians. MATERIALS AND METHODS: The anti-mycobacterial susceptibility test results of 502 strains, isolated from five university-affiliated hospitals, were analysed. The interpretation of the results and the need for second-line drug susceptibility test were judged according to the recommendation of NCCLS M24-A guidelines. RESULTS: The isolates from 10% (38/363) of treatment-navie patients and 61% (85/139) of re- treatment patients showed resistance to at least one of the anti-mycobactial agents; 3% (11/363) and 44% (61/139) of isolates from each group were multi-drug resistant. According to the recommendation by NCCLS, the percentage of patients not needing the susceptibility test results for second-line drugs were 96% for treatment-naive and 47% for re-treatment patients. CONCLUSION: Since the susceptibility test against first-line drug is sufficient for 95% of treatment- navie patients with tuberculosis patients, susceptibility test against second-line drugs may be performed only when it is necessary. As for the re-treatment patients with tuberculosis, susceptibility test for both first-line and second-line drugs should be performed simultaneously.