In order to know the enzyme activities of Fibricola seoulensis, an intestinal trematode of human and rodent in Korea, the enzyme histochemical method is applied. Activities of acid phosphatase (E.C.3.1.3.2) and non-specific esterase (E.C.3.1.1) were present in microvilli and glandular cells of tribocytic organ and the epithelium of the caecum.