Introduction: Surgical site infection is one of the most common causes of hospital acquired infection globally resulting in a significant burden in terms of patient morbidity, mortality and hospital costs. Globally surgical site infection rate ranges from 2.5% to 41%. Surgical site infection result in up to 10 billion dollar in costs every year. Compared to an uninfected patient, the patient with surgical site infection: Stays hospitalized 7 days longer; 60% more likely to spend time in the intensive care unit; 5 times more likely to be readmitted within 30 days of discharge; twice as likely to die. Objective: To determine the risk factors for surgical site infection in Felege Hiwot Referal Hospital on post-operative patients. Methods and Materials: Unmatched case control study was conducted. An interview with the patient, medical record review and observation in round time was used to collect data. Sample size was calculated by two proportion formula for unmatched case control study design using Epi-info. A total of 384 patients was involved in the study and multivariate logistic regression was used to identify the associated factors for surgical site infection. Result: Six risk factors for the development of Surgical site infection was identified in this study by multivariable analysis are: Body mass index<18.4 (AOR 2.68 with 95% CI 1.36 4.52), American Society of Anesthesiology grade classification greater than III ( AOR 9.52 with 95%CI 3.83 23.66), after the operation done patient who sleep in the corridor (AOR 2.02 with 95%CI 1.084 3.79),emergency procedures (AOR 2.22, with 95%CI 1.07 4.63) , surgeries which takes more than 2 hours (AOR 2.63, with 95%CI 1.090 6.38) and Surgeries which is done by resident doctors (AOR 2.31 with 95% CI 1.01 5.32) .Conclusion: The study suggests that nutritional status, ASA score classification, emergency surgery, surgeries done by resident doctors, surgeries which take more than 2 hours and after the operation patients stayed in the corridor were predictors of SSI. Most of the risk factors can easily be avoidable.. Key Words: Surgical site infection, risk factors, Ethiopia