<jats:title>Abstract</jats:title><jats:p>Seven ethnobotanically selected medicinal plants were screened for their antimycobacterial activity. The minimum inhibitory concentration (MIC) of four plants namely <jats:italic>Artemisia afra</jats:italic>, <jats:italic>Dodonea angustifolia</jats:italic>, <jats:italic>Drosera capensis</jats:italic> and<jats:italic> Galenia africana</jats:italic> ranged from 0.781 to 6.25 mg/mL against <jats:italic>Mycobacterium smegmatis. G. africana</jats:italic> showed the best activity exhibiting an MIC of 0.78 mg/mL and a minimum bactericidal concentration (MBC) of 1.56 mg/mL. The MICs of ethanol extracts of <jats:italic>D. angustifolia</jats:italic> and <jats:italic>G. africana</jats:italic> against <jats:italic>M. tuberculosis</jats:italic> were found to be 5.0 and 1.2 mg/mL respectively. The mammalian cytotoxicity IC<jats:sub>50</jats:sub> value of the most active antimycobacterial extract, from <jats:italic>G. africana</jats:italic>, was found to be 101.3 µg/mL against monkey kidney Vero cells. Since the ethanol <jats:italic>G. africana</jats:italic> displayed the best antimycobacterial activity, it was subjected to fractionation which led to the isolation of a flavone, 5,7,2′‐trihydroxyflavone. The MIC of this compound was found to be 0.031 mg/mL against <jats:italic>M. smegmatis</jats:italic> and 0.10 mg/mL against <jats:italic>M. tuberculosis</jats:italic>. This study gives some scientific basis to the traditional use of these plants for TB‐related symptoms. Copyright © 2008 John Wiley & Sons, Ltd.