Ethanol extracts from the different parts of B. orellana showed differential antimicrobial activity. It was found that the extracts of in vitro leaves showed maximum activity against Bacillus pumilus followed by the extracts from the roots and hypocotyls. The callus derived from different explants too showed antimicrobial activity. The leaf callus showed maximum activity. The zone of inhibition for the diluted extracts of in vitro hypocotyls and roots and their corresponding calli showed minimum zone of inhibition at concentration 24 mg/ml, whereas the diluted extract of in vitro leaves and leaf derived callus showed minimum zone of inhibition at 16 mg/ml.