One hundred fifty three kidney transplant recipients whose grafts functioned for longer than one year were evaluated for evidence of post-transplant diabetes mellitus (PTDM). Twenty-six patients (17%) developed PTDM. Patients with PTDM were older than controls (mean age 49.4 vs 37.9 years). There was no demonstrable association between sex of patients and PTDM. The body mass index (BMI) was persistently higher in patients with PTDM compared to controls, although the difference did not amount to statistical significance. The association of PTDM with HLA-A28, A30 and B8 observed in other studies was not seen in our patients. Similarly, neither the positive association of HLA-DR3 and DR4, nor the negative association of HLA-B7 and DR2 seen in population-based studies of insulin dependent diabetes mellitus, were seen in our patients with PTDM. To our knowledge, this is the first report that has looked into the association of HLA antigens and PTDM in Saudi Arabia.