Introduction: Impaired carbohydrate metabolism is a common finding in patients with chronic renal failure. Although intermittent hemodialysis results in a significant improvement of impaired glucose metabolism of uremia, complete normalization did not occur. Vitamin D₃ deficiency, it seems is linked with disturbance of glucose metabolism. A role of vit D in endocrine pancreatic function has been suggested. The aim of this study was to determine the effects of 1,25 (OH)2D3 treatment on glucose tolerance, insulin resistance and beta cell function in hemodialysis patients. Material and Methods: Of sixty-five patients with uremia on hemodialysis, twenty –seven who had never been treated with vitamin D or related drugs and without history of diabetes were selected for this study. These patients were randomly divided to two groups. group l were treated with oral calcitriol (0.5 mcg/day ) for 8 weeks and group ll received placebo for the 8 weeks. In all cases, before and 8 weeks after treatment fasting glucose, insulin, total cholesterol, triglycerides, HDL, LDL, calcium, phosphorous, PTH, HbA1C and blood sugar after 75 gr load of glucose were measured. Insulin resistance (homostatic model assessment-insulin resistance = HOMA–IR) and beta cell function (homostatic model assessment- insulin secretion =HOMA-SECR) were calculated and results of these measurements, before and after 8 weeks, in both groups were compared. Results: In group l, after calcitriol treatment, blood sugar after 75 gr load of glucose (p= 0.045), HOMA –IR (p= 0.035), HbA1C (p=0.00), total cholesterol (p=0.037), and triglycerides (p=0.036) decreased, whereas calcium levels increased, significantly (0.014) changes in other parameters were not significant. In group ll (without treatment) after 8 weeks of observation, fasting blood sugar (p=0.002), HbA1C (p=0.004), HOMA –IR (p=0.036) significantly increased and beta cell function decreased significantly (p= 0.032) again alterations in other parameters were not significant. Conclusion: These results seem to confirm that the active form of vitamin D influences glucose and lipid metabolism, by the improvement of insulin resistance.