BACKGROUND: TB has remained a significant public health concern from historical times to the present day. Each year, growing drug resistance problems necessitate the discovery of new drugs and drug precursors for TB treatment. Morusin is an important flavone found in the bark of white mulberry (Morus alba L.) with anti-oxidant, antimicrobial, anti-tumour, anti-inflammatory and antiallergic activity.OBJECTIVE: To determine the anti-TB efficacy of morusin on Mycobacterium tuberculosis strains.DESIGN: Anti-TB efficacy of morusin was tested on H37Ra (American Type Culture Collection [ATCC] 25177), H37Rv (ATCC 27294), ATCC 35822 (isoniazid [INH] resistant), ATCC 35838 (rifampicin [RIF] resistant), and ATCC 35820 (streptomycin [SM] resistant) standard strains and its efficacy was determined using nitrate reductase assay (NRA).RESULTS: The minimum inhibitory concentration (MIC) of morusin was tested in the range of 53.83â-"0.21 μg/ml. The MIC for H37Ra (ATCC 25177), H37Rv (ATCC 27294) and ATCC 35838 (RIF-resistant) strains were found to be 6.72 μg/ml, and this was 13.45 μg/ml for the ATCC 35822 (INHresistant) and ATCC 35820 (SM-resistant) strains.CONCLUSION: To consider morusin as a viable alternative or precursor drug for TB treatment, it is imperative to conduct an exhaustive examination of its mechanism of action and conduct in vitro studies using clinical isolates.