The drug resistance of 1,860 human mycobacterial strains was analysed. Of these 987 were isolated from new cases and 873 from cases who underwent a treatment for pulmonary tuberculosis. The investigation lowered 3 years (1986-1988). It resulted that the frequency of primary resistance was of 23.8% and that of secondary resistance was of 47.6%. As part of primary and secondary resistance, mono-resistance to SN and bi-resistance to SN and INH were the most common.