Abstract Fructose has been recommended as an intravenous energy source during parenteral nutrition for patients with hepatic disease, uncontrolled diabetes mellitus, and in the postoperative state. Fructose is metabolised in the liver where it causes increased lactate formation, high-energy-phosphate depletion, increased uric-acid formation, and inhibition of protein synthesis. This results in increased concentrations of blood-lactate and serum-uric-acid. In hepatic disease and anoxic states fructose infusion can lead to lactic acidosis. In diabetic ketoacidosis the rises in blood lactate and uric acid which normally occur will be exacerbated. Great caution should be exercised before using intravenous fructose.