Derivatives of 4(7)-methyl- and 5,6-dimethyl-benzimidazolyl-2-mercaptoacetic acids.

Esters, hydrazides and hydrazones of the in title mentioned acids were prepared and screened for tuberculostatic activity. The strongest activity (MIC at 15-6 mug/cm3) was shown by hydrazide 4 and its hydrazone 4a.