Abstract: Clausenacoumarine is a compound isolated from the leaves of Clausena lansium (Lour.) Skeels which grows widely in South China. The studies show that clausenacoumarine can lower blood glucose level in normal mice and alloxan diabetic mice at 200 mg/kg.d for three days orally, and antagonize the elevation of blood glucose caused by injecting adrenaline in normal mice. No effect on blood lactic acid was observed.