A series of pyrazine-2-carboxylic acid hydrazide derivatives were synthesized and screened for their activity against Mycobacterium tuberculosis. The results show that pyrazine-2-carboxylic acid hydrazide-hydrazone derivatives 3a-l were less active than pyrazinamide. In contrast, the N4-ethyl-N1-pyrazinoyl-thiosemicarbazide 4 showed the highest activity against M. tuberculosis H37Rv (IC90 = 16.87 µg/ mL). Details of the structure-activity and structure-cytotoxicity relationships are discussed.