University Department of Chemistry, Bhavnagar University, Bhavnagar-364 002 Manuscript received 12 January 1981, revised 3 October 1988, accepted 1 February 1989 Fifteen new 3-(N-arylcarbamoylmethylhydrazino)-1,2,4-triazino[5,6-b]indoles have been synthesised and screened for antibacterial activity. Some of them are active against gram + ve and - ve bacteria like S \({aureus}\) and E. coli.