Aim: The aim of the present study is to identify bacterial aetiology of surgical site infections. Material and methods: The study was a cross sectional study which was carried in the Department of Microbiology, Anugrah Narayan Magadh Medical College and Hospital, Gaya, Bihar, India for one year. Using sterile cotton swabs, two pus swabs/ wound swabs were collected aseptically from each patient suspected of having SSI. Gram stained preparations were made from one swab for provisional diagnosis. The other swab was inoculated on nutrient agar, 5% sheep blood agar (BA) and MacConkey agar (MA) plates and incubated at 37°C for 24-48 hours before being reported as sterile. Growth on culture plates was identified by its colony characters and the battery of standard biochemical tests. All the isolates were tested for antimicrobial susceptibility by Kirby Bauer disk diffusion technique on Muller Hinton Agar. Results: Out of 230 samples, 120 samples were culture positive (52.17%). Among 120 positive samples 67(55.83%) were males. Maximum no. of culture positive samples in age 20- 30 years (32.5%) followed by 30-40 (17.5 %) and then followed by 40-50 (15.83%) of age group respectively. Out of 120 culture positive samples S.aureus (26.67%) was the most common pathogen isolated followed by Escherichia coli. (23.33%), Citrobacter spp. (15.83%) and Pseudomonas aeruginosa (9.17%), Klebsiella spp 10(8.33%), CONS 8(6.67%), Enterobacter spp. 7(5.83%), Acinetobacter spp 3(2.5%) and Proteus spp. 2(1.67%) respectively. Conclusion: We conclude that SSIs are common among patients undergoing surgeries.