Post liver transplant Diabetes Mellitus (PTDM) is a common complication after liver transplantation and is believed to be multifactorial. In this study we investigated the prevalence and risk factors of developing diabetes mellitus in patients who underwent liver transplantation between 1994 and 2006 in Shiraz organ transplant center. This retrospective study was performed to investigate the prevalence and risk factors of PTDM in 170 liver recipients. Patients were considered to meet the criteria for DM if they had fasting glucose≥126mg/dL or if they were taking insulin or hypoglycemic agents at the time of this study. The influence of age, gender, HBV, HCV infection and immunosuppressive medications was also studied. Data were collected by review of patients medical records and analyzed with SPSS software. Results: The mean level of fasting plasma glucose before transplantation was (103.9±50.7) while it was (125.9±78.7) after transplantation. 44 of 170 patients (25.88%) developed DM after transplantation. Among them33 patients were male and 11 patient were female (P<0.05). HBV infection was significantly correlated with developing PTDM (P<0.05) while HCV infection and immunosuppressive medication was not predictors of PTDM (P>0.05). Diabetes Mellitus is common metabolic complication after liver transplantation. This study showed that development of PTDM is associated with male gender and HBV infection in Iranian liver recipients.