The acidifying effect of intravenous (IV) ascorbic acid was studied in seven healthy adult volunteers. After obtaining baseline urine and blood samples, 2-g IV doses of ascorbic acid were administered to each subject during a 20-minute period. Venous blood samples were obtained at times 0.5, 1, and 2 hours, and urine was collected at times 0.5, 1, 2, and 3 hours. Our results show that venous blood pH, plasma bicarbonate concentration, urine PCO2, and urine bicarbonate excretion did not change significantly during the study period. Urinary titratable acidity, ammonium excretion, and net hydrogen ion excretion decreased, and urinary pH actually showed a significant rise at two hours. We therefore conclude that IV ascorbic acid administered in recommended doses does not effectively acidify urine.