Objective The objective of the present study was to evaluate the feasibility of using microscopic observation drug susceptibility (MODS) assay for the simultaneous detection of multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) through the detection of resistance to rifampicin (RMP),isoniazid (INH),ofloxacin (OFX) and kanamycin (KM) in Mycobacterium tuberculosis clinical isolates.Methods 208 archived clinical isolates of M.tuberculosis were used to compare MODS with the conventional proportion method (PM) for rapid detection of resistance to RMP and INH,as well as to the second-line drugs OFX and KM.