Antimicrobial activity of the ethanolic extract of Strychnos nux vomica seeds was studied. The invitro antimicrobial activity was performed by agar disc diffusion method. The most susceptible bacteria gram positive bacteria identified was Staphylococcus aureus and gram negative bacteria’s were Eschershia coli and Klebsiella pneumoniae. All the fungal species showed resistance to the extract. The effects of extract on these microbes were compared against the standard antibiotics such as ampicillin and amphotericin with 20μg/disc. In this study, Strychnos nux vomica seed extracts showed maximum inhibition against the gram negative bacteria and less or no inhibition against the fungal organisms tested. From this study it was identified that ethanolic seed extracts of this tree could be used to control the above said microbes.