Post transplant diabetes mellitus (PTDM) is a frequent complication of renal transplantation (Tx), reported in 9 to 36% of cases. This study was conducted to determine the prevalence and risk factors of PTMD in Iranian renal Tx recipients. In this cross-sectional study 300 renal Tx patients who regularly visited a referral Tx laboratory, were studied between March and August 2007. Questionnaires including clinical data were filled and blood samples were taken for biochemical studies. PTMD was defined as DM after renal Tx without a pre-Tx Hx. There were 184 (61.3%) male and 116 (38.7%) female patients with a mean age of 41.2 ± 13.5 years. The mean post-Tx interval was 67.4 ± 48.6 months. PTMD was seen in 24 patients (8%). The mean interval for development of PTMD was 19.9 ± 31.5 months. The mean age of patients with PTMD was significantly higher than those without PTMD (49.4 ± 13.4 yrs vs. 40.6 ± 13.4 yrs, p< 0.005). Mean serum HDL was higher in PTMD compared to non- PTMD patients (71.4 ± 21 vs. 58.6 ± 14.6, p<0.005) and there was a trend for higher serum LDL in PTMD patients (109.2 ± 29.5 vs. 96.2 ± 25.2, p=0.06). History of a recent admission was more frequent in PTMD patients (58.3% vs. 28.7%, p< 0.005) so was the history of HCV infection (6% vs. 1%, p< 0.01). There was no significant difference between the dose of prednisolone, cyclosporine, cellcept, azathioprine, and atenolol, mean body mass index, family history of DM, Tx rejection, history of CMV infection and frequency of positive anti-HCV antibody between 2 groups. Our study showed an 8% prevalence of PTMD. Mean age, history of admissions and HCV infection and mean plasma HDL and LDL levels were higher in PTMD patients. Our study didn’t prove any relationship between PTMD and the other reported risk factors. Prospective cohort studies are suggested.