Background: Post reperfusion syndrome (PRS) is a relatively common and life-threatening complication during orthotopic liver transplantation (OLT). It is associated with poor patient and transplanted liver outcomes., Objective: This study aimed to compare the risk factors of PRS during OLT., Design: Clinical-epidemiological observational retrospective study., Setting: We gathered the records of patients who underwent OLT in 3 years, from May 22, 2016, to May 22, 2019, in Namazi and Bu-Ali Sina organ transplantation hospitals., Patients: In this study, we assessed 1182 patients who underwent OLT. Patients were divided into two groups based on the presence or absence of PRS., Main Outcome Measures: Diagnosing the predictors of PRS was the primary outcome of this study., Results: Results showed that age > 60 years, Child-Pugh scores C, higher Model End Stage liver disease score, and preoperative sodium < 130 mmol/l (parameters of the liver recipient), increase in cold ischemic time (the donors' parameters), and the classical technique (the surgical parameters) were the strong predictors of PRS., Conclusions: The results indicated that underlying liver disease was not the predictor of PRS in the presence of other risk factors; therefore, clinicians have to consider these risk factors in patients undergoing OLT., (© 2022. The Author(s).)