We have studied the effects of buckwheat diet on serum glucose and lipid metabolism in 9 NIDDM volunteers during 2 weeks. The subjects were given dietary counseling in their own homes at 2-3 day intervals throughout experimental periods and the dietary intake were determined by interview and record methods. The intake of calorie, carbohydrate, protein and fat during the buckwheat diet period were not significantly different compared with control diet and body weight was maintained within 1-2kg. The mean total glycohemoglobin, fructosamine, total cholesterol and LDL-cholesterol levels at the end of buckwheat diet were significantly lower than the end of control diet (P<0.05). Fasting serum glucose, insulin and HDL-chloesterol levels were slightly decreased. The mean triglyceride level was increased but it was not significant. These results indicate that buckwheat diet is an effective therapeutic regimen for the control of metabolic derangements in diabetes mellitus.