OBJECTIVE The aim of this study was to identify risk factors for surgical site infections and to quantify the contribution of independent risk factors to the probability of developing infection after definitive fixation of tibial plateau fractures in adult patients. METHODS A retrospective analysis was performed at a level I trauma center between January 2004 and December 2010. Data were collected from a review of the patient's electronic medical records. A total of 251 consecutive patients (256 cases) were divided into two groups, those with surgical site infections and those without surgical site infections. Preoperative and perioperative variables were compared between these groups, and risk factors were determined by univariate analyses and multivariate logistic regression. Variables analyzed included age, gender, smoking history, diabetes, presence of an open fracture, presence of compartment syndrome, Schatzker classification, polytrauma status, ICU stay, time from injury to surgery, use of temporary external fixation, surgical approach, surgical fixation, operative time, and use of a drain. RESULTS The overall rate of surgical site infection after ORIF of tibial plateau fractures during the 7 years of this study was 7.8% (20 of 256). The most common causative pathogens was Staphylococcus aureus (n=15, 75%). Independent predictors of surgical site infection identified by multivariate analyses were open tibial plateau fracture (odds ratio=3.9; 95% CI=1.3-11.6; p=0.015) and operative time (odds ratio=2.7; 95% CI=1.6-4.4; p<0.001). The presence of compartment syndrome (odds ratio=3.4; 95% CI=0.7-15.9; p=0.119), use of temporary external fixation (odds ratio=0.5; 95% CI=0.2-1.7; p=0.298), and ICU stay (odds ratio=1.0; 95% CI=1.0-1.1; p=0.074) were not determined to be independent predictors of surgical site infection. CONCLUSIONS Both open fracture and operative time are independent risks factors for postoperative infection.