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Background & Objective: About 1.3 billions people are infected with Tuberculosis (TB) all over the world. There is a close relationship between the quality of TB treatment and the rate of drug resistance. The recurrence epidemy of TB and increased resistance to some drugs was the basis for the WHO to suggest the directly observed short course treatment strategy or (DOTS) strategy, for the TB patients. Materials & Methods: This research was a cohort study and aimed to evaluate the epidemiological finding, the clinical basis and strategy of DOTS on improving, and prevention from failure of treatment and was compared with non-DOTS procedure. Sample population were total of 260 smear positive patients that had been under study for a period of 2 years (1999-2000). All of the patients were new cases. SPSS software and Fisher exact test was used to analyzed the data. Results: The rate of treatment failure in DOTS strategy in the beginning of 5th month was 1.7%, but in the control group the failure in the same period was 7.3% (P<0.05). Conclusion: This study indicated that the DOTS strategy is substantially increasing the success rate of TB treatment.