Patients with diabetes have an increased risk for allograft rejection. Hyperglycemia is also common following renal transplantation in patients without diabetes. This study was conducted to evaluate the relationship of perioperative serum glucose levels and acute rejection (A.R) in patients without a history of diabetes. In Dr Shariati Hospital, 100 non-diabetic patients (pt) who underwent renal transplantation from living unrelated (84 pt) or related (7 pt) donors, or deceased donors (9 pt) were studied. Blood glucose was measured immediately following surgery and every 6 hours during the first 48 hours post transplant and patients were followed for 1 month for occurrence of acute rejection. A.R was defined by clinical criteria and by >=20% increase in baseline serum creatinine. Renal Biopsy was performed in 13 patients and showed acute tubular necrosis in 2 and A.R in 11 according to Banff criteria. Mean age of patients was 35.2 ±13.9 years and 52% were men. A.R occurred in 33% of 100 patients studied. There was no significant correlation between A.R and donor’s or recipient’s age or sex, donor graft function, type of donor and treatment. The mean blood glucose level immediately after surgery in patients with A.R and without A.R was 249.67±61.78 mg/dl and 148.82±73.35, respectively (p<0.0001). Hyperglycemia in the first 2 days post transplantation did not correlate with A.R. There was a significantly greater risk of acute rejection, in patients who had a higher blood glucose level immediately after kidney transplant surgery. Blood glucose monitoring during and immediately after surgery may be helpful for predicting and possibly reducing the risk of acute transplant rejection.