Phyllanthus amarus is an indigenous medicinal plant, with a folk reputation as hypoglycemic agent in Central and Southern India. In the present investigation hypoglycemic activity of ethanolic leaf extract of Phyllanthus amarus was evaluated using alloxan induced hyperglycemic mice. Blood glucose levels of all the mice of each group were tested before the treatments on fasting mice and then tested after 1,h 2,h and 4h of administration of a single dose of the extract(400 mg/kg body weight) or standard antidiabetic drug glibenclamide (600 μg/kg body weight.) The blood glucose level was measured using glucometer. The diabetic mice treated with extract showed a significant (P≤0.05) decrease in blood glucose level after the intervals of 1h, 2h and 4h. The hypoglycemic activity was comparable to that of the reference drug glibenclamide. The present investigation revealed that the ethanolic leaf extract of Phyllanthus amarus possesses a potent hypoglycemic activity. The possible mechanism may be the stimulation of β cells and subsequent release of insulin and activation of the insulin receptors. The plants hypoglycemic action may be by potentiating of pancreatic secretion of insulin.