This study was conducted to investigate the effect of oral administering kefir on blood glucose levels in diabetic mice. Kefir(10 ㎖/㎏body weight) was orally administered to diabetic mice twice daily for 45 days. Diabetic mice fed saline or 10% skim milk were used as a control. No significant difference in feed intake and weight gain were observed among the treatments. Compared to the saline-fed or skim milk-fed group, blood glucose in the kefir-fed group decreased significantly at 45 days(p<0.05). At 45 days, serum triglyceride and non-esterified fatty acid concentrations in diabetic mice fed kefir decreased significantly compared to those of the saline and skim milk groups(p<0.05). Both high density lipoprotein and low density lipoprotein concentrations were not significantly different among the three treatment groups. In conclusion, the symptoms of diabetic mice improved when kefir was fed for >45 days.