The antimicrobial activity of 2,4,6,8-tetraaryl-3,7-diazabicyclo [3.3.1] nonan-9-one and its derivatives was assessed against gram negative microorganism, Escherichia coli (diarrheal pathogen). Screening was performed by disc diffusion method and the zone of inhibition from 9 mm to 17 mm was observed. All the four derivatives of drug at various concentrations are taken for the study. The comparative study amongst these four drugs for their antimicrobial activity was also done.