Post transplant Diabetes Mellitus (PTDM) has several pre- and post-transplant risk factors. The incidence and risk factors of PTDM were retrospectively evaluated in 2117 kidney allograft recipients from June 1985 through March 2004.Type and dosage of immunosuppressants, pre-transplant weight and HLA phenotypes in PTDM patients were compared with 61 matched controls. 61 cases (2.8%) of recipients developed PTDM requiring insulin or oral hypoglycaemic therapy, out of which 47.5% were male and 52.5%were female, although only 35% of our recipients are female. Onset occurs at a mean of 489 days following transplantation. Patients receiving; 15mg/d. prednisolone developed PTDM more than those on <15mg/d. (p=0.000). Similarly PTDM was more frequent in patients received; 300 mg/d cyclosporine compared to those on <300mg/d. (p=0.015). Mean weight in PTDM cases and controls was 65±13.4 kg and 57±13.6 kg, respectively. (p=0.005). HLA-DR 6 was found in 12.2% of controls but in none of the PTDM group (p=0.002). Conversely HLA-DR 8 was seen only in PTDM patients (p=0.012). In addition HLA B-26 was more common in PTDM patients (p=0.02) and HLA-DR 52 more frequent in controls (p=0.025). Our findings show that, female sex, dosage of prednisolone and cyclosporine, pre-transplant weight and genetic factors are associated with an increased risk of PTDM. The rate of PTDM appeared independent of weight gain in the first year post-transplant. Protection against PTDM may be present in patients with HLA-DR 6 and possibly HLA-DR 52.Conversely higher incidence of diabetes has been associated with HLA-DR 8 and HLA-A 26.