Ingestion of glucose has been confirmed to lowers blood pressure in individuals with autonomic dysfunction (1). Whether glucose drink affects cardiovascular responses during orthostatic stress in young healthy individuals, particularly in Africans is not known. We therefore sought to investigate the hypothesis that glucose drink will reduce orthostatic tolerance in normal young African men. In a randomized controlled cross-over design, eleven men (19.8 ± 0.4 kg/m2; 22.4 ± 0.8yr) ingested nothing, water (250ml) and 30% glucose drink 10min before standing on three separate days. We measured supine and standing systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and blood glucose levels. Orthostatic tolerance was evaluated as the time to presyncope for the period of motionless standing or until presyncopal symptoms were observed (2) and syncope have been found to accounts for 1-3% of admissions to the emergency room (3-4). Throughout the first 60min of upright posture, 81.8%, 23.9% and 45.1% of 11 subjects experienced presyncopal symptoms when ingested nothing, water and 30% glucose drink, respectively. Water ingestion improves tolerance to orthostatic stress significantly while ingesting glucose drink significantly reduced orthostatic tolerance. Increased HR induced by standing was significantly improved, while the increase in SBP was attenuated when 30% glucose water was ingested. Conversely, increased DBP was not significantly affected by glucose drink. Ingestion of glucose drink led to a considerable increase in blood glucose level during orthostatic challenge when compared to when nothing or water was ingested. This study shows that glucose-enriched drink reduces orthostatic tolerance, and this is correlated with enhanced tachycardia and attenuated SBP response. The findings imply that glucose-enriched fluid may not be suitable for individuals predisposed to orthostatic intolerance.