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Sputum culture and sensitivity tests for Mycobacterium Tuberculosis were performed in 329 patients who had received treatment for more than six months, with persistent positive smear and deteriorating radiological lesions. High prevalence of acquired drug resistance (ADR) 63.4% was found during the last 10 years with still higher figures during the last five years (81.48%). INH resistance was more commonly encountered, followed by resistance to other drugs. Significant increase in the ADR was observed for Pyrazinamide and Rifampicin from 4.01% to 8.33% and 3.17% to 17.59% respectively.