Abstract Rahman M. Saidur and Mettrick D. F. 1982. Carbohydrate intermediary metabolism in Hymenolepis microstoma (Cestoda). International Journal for Parasitology 12, 155–162. Studies on the intermediate and end-products of glucose catabolism indicated that Hymenolepis microstoma possesses branched pathways for carbohydrate metabolism. In vivo the parasite produces lactate, succinate, acetate and propionate. Under in vitro anaerobic conditions in the presence of CO 2 H. microstoma can largely maintain its in vivo metabolic profile, whereas under aerobic conditions, especially in the absence of CO 2 , worm ATP and total adenine nucleotide levels were greatly reduced. The results suggest that CO 2 -fixation is a vital step in the metabolic pathways of H. microstoma . Comparison of mass action ratios with the apparent equilibrium constants indicate that hexokinase, phosphofructokinase and pyruvate kinase may play regulatory roles in glucose metabolism.