Objective: find more effective regimen for giving prophylactic antibiotics postoperatively in order to limit the surgical site infection rate to minimum. Methodology: the study was carried out in general surgical unit of Jinnah hospital Lahore over a period of six months using a sample size of 60 patients operated for clean and clean contaminated surgeries.30 patients were given 3 doses of cephalsporin while 30 were given 6 doses of the same antibiotic.consent was taken prior to evaluation The patients were monitored for development of any infectious signs and symptoms at the site of surgery during their stay in the hospital via routine post op rounds. Results: there was no difference between the infectious rate of both doses given post operatively if any.chi suare test was applied and it showed insignificant association between doses and development of infection. Conclusion:the number of dose does not effect the development of surgical site infection if any in post operative patients. Key words: Surgical site infections, cephalosporins.