Histochemical studies have revealed hydrolytic enzyme activity in the redial tegument and caecal epithelium of Fasciola hepatica. A number of the hydrolases are known to be lysosomal marker enzymes and it is thought that they may be involved in intracellular digestion. The larval stages have also been shown to be reactive for succinate dehydrogenase and phosphorylase, but not for glucose-6-phosphatase.