Nine endurance-trained men exercised on a cycle ergometer at ~68% VO₂ peak to the point of volitional fatigue (232 ±14 min, mean ±SE) while ingesting an 8% carbohydrate solution, to determine how high glucose disposal could increase under physiological conditions. Plasma glucose kinetics were measured using a primed, continuous infusion of 6,6-²H glucose and the appearance of ingested glucose assessed from 3-³H glucose that had been added to the carbohydrate drink. Plasma glucose was increased (P<0.05) after 30 min of exercise, but thereafter remained at the pre-exercise level. Glucose Ra increased throughout exercise, reaching its peak value of 118 ± 7 µmol.kg^-1.min^-1 at fatigue, while gut Ra increased continuously during exercise peaking at 105 ± 10 µmol.kg^-1.min^-1 at the point of fatigue. In contrast, liver glucose output never rose above resting levels at any time during exercise. Glucose Rd increased throughout exercise, reaching a peak value of 118 ± 7 µmol.kg^-1.min^-1 at fatigue. Assuming 95% oxidation of glucose Rd, estimated exogenous glucose oxidation at fatigue was 1.36 ± 0.08 g.min^-1. The results of this study demonstrate that glucose uptake increases continuously during prolonged, strenuous exercise when carbohydrate is ingested and does not appear to limit exercise performance.