The present study was conducted to investigate the antibacterial effect of Albizzia lebbeck (powdered bark) against human pathogens such as Escherichia coli (E.coli) and Pseudomonas aurogenosa (P. aurogenosa). Minimum inhibitory concentration (MIC) of the aqueous powdered bark extract of Albizzia lebbeck (AL) was determined using the following concentrations 200 mg/ml, and 400 mg/ml. It indicates that the concentration of test sample is directly proportional to the zone of inhibition. Zone of inhibition of AL at 200mg/kg and 400 mg/kg is 13 mm & 18 mm respectively for E.coli, whereas zone of inhibition of AL 200mg/kg and 400 mg/kg is 17 mm & 18 mm respectively for P.aurogenosa. This study indicates that Albizzia lebbeck has an important antimicrobial effect, which justifies its potential use in development of new antimicrobial medicines for the treatment and management of diseases.

Key Words: Albizzia lebbeck, Antibacterial activity, E-coli, P.aurogenosa