Abstract: Objective For observation the tolerance of nontuberculosis mycobacteria to anti tuberculosis drugs.Method Ninety strains of nontuberculosis mycobacteria were taken for strain identification and sensitivity test to drugs with traditional methods.Results All strains of non tuberculosis mycobacteria were shown with highly tolerance to PAS,and high to SM,INH,RFP,EBM and less(sensitive)to KM,TH.Among them,the strain of M.Kansasii presented more sensitive to anti tuberculosis drugs.The others such as M.Avium,M.Intracellulare,M.Triviale,M.Terrae,M.Fortuitum,etc.were showed more tolerance to drugs,By the way,the tolerances of non tuberculosis mycobacteria were quite different between high or low concentrations of these six drugs except to the PAS.These explains why a lot of non tuberculosis mycobacteria are resistant naturally to anti tuberculosis drugs.Conclusion To research a new drug and making a further proper therapeutic measure are necessary.

Key words: Non tuberculosis mycobacteria, Drug tolerance