A new series of N-(3/4-substituted phenyl) 4/5-chloro-2-methoxybenzamides and their thioxo analogues have been synthesised and evaluated for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, as well as the two atypical strains Mycobacterium kansasii and Mycobacterium avium. Five of the most active compounds were evaluated for cytotoxicity and their ability to inhibit mycobacterial isocitrate lyase, which is responsible for latent survival of Mycobacterium. The results showed that benzthioanilides were more active than the corresponding benzanilides. The most active compound, 4-chloro-2-methoxy-N-(3,4-dichlorophenyl)benzothioamide (4e), had a minimal inhibition concentration (MIC) against M. tuberculosis of 2 μmol L(-1), which was better than the activity of the previously published corresponding salicylanilide.