Abstract: The effects of pyquiton and albendazole on Clonorchis sinensis in rats were studicd by means of scanning clcctron microscopc. Pyquiton and albendazole were administered orally at a single dose of 300 mg/kg and 150 mg/kg respectively. Swelling and vacuu- lization of the tegument of worms occured 2hr after pyquiton administeration. 4-24 hr later vacuoles ruptured, and crosion of tegumental tissues appeared. As the alteration progressed, the outer tegumental layer disruptured 36-48 hr later. After albendazole administration, swelling, protrusion formation and erosion were observed on the tegument 24 hr, 36 hr and 48 hr later respectively. The results indicate that both pyquiton and albendazole have destructive cffcct on the tcgument of Clonorchis sinensis.