Aim: The aim of this study is to estimate the bactericidal activity of bacteriocin against the common human pathogens. A total of 62 specimens were collected from patients attending the department of surgery, Karpaga Vinayaga Institute of Medical sciences and Research Centre, during a period of six months. Methodology: Specimens collected were superficial pus swab from the wound, deep tissue biopsy and scraping from the base of the ulcers. Samples were cultured on Blood agar (BA) and MacConkey agar (MA). The plates were incubated at 37C over night. The aerobic organisms were identified by standard microbiological procedures as described in Bailey and scott__ampersandsignrsquo;s Daignostic Microbiology. (Finegold et al.1986).(1) The E coli which was isolated and identified was used in the preparation of crude bacteriocin.( 2) It was purified by Ammonium sulphate precipitation(3)and concentrated by centrifugation. Desalting of protein was done by dialysis method.(4) The protein concentrations of these purified bacteriocin was determined by Lowry__ampersandsignrsquo;s method.(5) Bacteriocin prepared from E coli was subjected for its bactericidal activity against some human pathogens by minimum inhibitory concentration method. Optical density (OD) of the culture was measured at 660 nm using spectrophotometer. Bactericidal activity of bacteriocin against human pathogens was estimated. Results: The results were analyzed, most of the pathogens need a very low concentration of the bacteriocin for the minimum inhibitory concentration (MIC).We observed that there is a slight variation in MIC among the different bacterial pathogens. Conclusion: In General when the concentration of the bacteriocin increased then the OD values of the culture tubes were decreased. In conclusion Bacteriocin not only have the bacteriocidal activity but also dose dependent in different bacteria.