Utilization of carbohydrate by Eimeria tenella sporozoite was investigated under aerobic condition. The decrease of amylopectin reserve in the sporozoite cultivated at 37°C was suppressed by glucose, fructose, mannose and maltose but not by galactose, glycogen, sucrose, lactose, pyruvate and glycerol. When the sporozoites were incubated at 41°C in the presence of ¹⁴C-glucose, the change of radio activity showed that the sporozoites took in glucose from out of their body and metabolize it to excrete briskly. C0₂ production from glucose was observed at the beginning of incubation.