Essential oil of Artemisia annua L. was investigated to find out its toxicity and physiological aspects on the slug Agriolimax agrestis, in controlled conditions (8±1°C, 75±5 RH and 14:10 LD). The slugs received different concentrations of essential oil treated radish leaves in methanol, while the control received methanol alone. LC10, LC30, LC50 and LC90 values were estimated at 4.67, 5.3, 5.81, 7.25%, respectively. The effect of the essential oil on some important enzymatic components like; cytochrome P450 monnooxygenase, acid phosphatase, alkaline phosphatase, lipase, amylase and protease were significantly increased compared to the control. These results indicate that the plant Artemisia annua L. not only shows toxicity but also shows some irreversible effect on some important biochemical components and deserves further investigation