An alcoholic extract of Zizyphus sativa leaves was tested for hypoglycemic activity in normal and alloxan-diabetic rats. Single (100-400 mg/kg) oral doses of extract to normal animals showed a dose-dependent statistically significant lowering of blood glucose 2, 4 and 6 h later. The effect was most pronounced at 6 h with blood glucose returning to control values at 24 h. In alloxan-diabetic rats, no significant effect was observed with extract and tolbutamide. The minimum lethal dose was greater than 3000 mg/kg, orally in mice.