Carbohydrate metabolism of Ascardia galli and Heterakis gallinae was studied after their exposure in vitro to 10(-2) to 10(-5) M piperazine adipate and parbendazole for 10 to 60 min. Following treatment with 10(-2) M piperazine adipate O2 uptake was reduced by 87% in A. galli and 70% in H. gallinae, while parbendazole (10(-2) M) reduced O2 uptake by 70% and 86%, respectively. Glycogen contents were reduced significantly by 10(-2) M piperazine adipate in both the worms, while lactic acid level was enhanced. Parbendazole, however, did not cause any significant change in glycogen contents and lactic acid level in either parasite.