Postoperative wound infection is a severe problem in the surgical specialties, which can cause mortality, morbidity and economic burden. In most post-operative SSIs the causative pathogens originate from endogenous flora of the patient’s skin, mucous membranes or hollow viscera. Objectives of the present study were to study the frequency of various types of bacteria. The study was carried out in general ward of the North Indian hospitals. The samples from the 50 post-operative patients were evaluated for the study. Samples were taken from the patients during the period of surgical wound dressing before the wound was cleaned with antiseptic solution. The swab was inoculated onto plates of MacConkey agar and 5% Sheep blood agar by rolling the swab over the agar and streaked. These plates were incubated at 37° C for 24- 48hours. The present microbiological study has determined the commonest bacteria responsible for the post-operative wound infectons. There was predominance of commonly isolated bacterial species were S. aureus, P. aeruginosa and E. coli.