The antihyperglycaemic activity of Tetracarpidium conophorum nut (walnut) was investigated in albino rats. A total of 20 albino rats were used for the study. The rats were divided into five groups (A-E) of four rats each. Diabetes were induced in the rats except four which served as the positive control group A. Groups B (negative control), C, D, and E contain diabetic rats each with blood sugar level ≥17.00 mmol/L. Groups A and B were fed on 85.2 g of top feed grower over the test period. Test groups C, D, and E were fed on 21.3 g, 42.6 g, and 85.2 g of walnuts, respectively, and their fasting blood sugar (FBS) levels were checked on daily basis. Fasting blood glucose levels of the test groups were significantly lower than negative control P < 0.05, for 3rd, 7th, and 10th days of the test. There were also significant increase in the body weight and hemoglobin concentration and a decreased urine output of the test group compared with the controls. These results indicate that Tetracarpidium conophorum nut (walnut) has an antihyperglycemic effect in diabetic rats.