Diabetic and non-diabetic subjects are not affected by similar complications after kidney transplantation. Although different patterns of hospitalization have been reported in diabetics and non-diabetics, differences in costs have not been well considered. The aim of this study was to compare diabetic and non-diabetic kidney recipients with respect to the costs of re-hospitalization. Study design was a retrospective review of all patients who had undergone renal transplantation in Baqiyatallah Hospital between the years 2001 and 2005. Subjects consisted of 68 diabetic and 302 non-diabetic patients. Costs were categorized into the following groups: inpatient rooming, medical-surgical-supply, paraclinic, drug, radiology-nuclear, operating, special services, and miscellaneous costs. Figures were recorded as US dollars (9000 Iranian Rials = 1 US dollar). Costs were compared between the two groups of patients. Compared with non-diabetic subjects, diabetics had significantly higher charges of total costs ($ 1385± 1371 vs 239± 124), inpatient rooming ($ 268± 318 vs 122± 260), medical-surgical-supply ($ 93± 106 vs 57± 82), paraclinic ($ 90± 73 vs 59± 164) and special services ($ 83 ± 73 vs 20± 30) (p<0.05). Other costs, including drug ($ 50± 69 vs 34± 56), radiology-nuclear ($ 65± 83 vs 49± 83), operating ($ 79 ± 63 vs 121 ± 240), and miscellaneous costs ($ 23 ± 33 vs 19± 29), were not significantly different between the two groups (p>0.05). Among renal transplant recipients, diabetics impose higher costs of inpatient services on the health system. In countries with large proportions of diabetic kidney recipients, health care systems should expect higher amounts of inpatient re-hospitalization expenses in the post-transplantation phase.