To evaluate the clinical value of PCR SSCP to detect the rPOB, katG and rPSL resistance genes in M. tuberculosis, the mutation of genes and results of drug sensitive test in strains of M. tuberculosis isolated from 123 patients and grown with Bactec 960 were analyzed, drug sensitive test and polymerase chain reaction single stranded conformation polymorphism (PCR SSCP) were performed. Clinical therapeutic effect was evaluated. In nearly one third of the patients, resistance against one drug was found in primary treatmnent. The mutation rate of RFP, INH and SM drug sensitive isolates was 6 2%, 10 8%, and 25 4%, respectively, while that of drug resistant isolates was 60 2%, 48 0%, and 61 5%, respectively. The magnitude of drug resistance was in accordance with the increase in mutation rate of genes. Detection of the resistance genes could be a new approach in guiding treatment, and it might complement drug sensitive test in clinical management of tuberculosis patients.