Serum phosphate (S-P) and 2,3-diphosphoglycerate (2,3-DPG) were monitored for 10 days after severe burn trauma in 16 patients treated with total parenteral nutrition, including supplementation with 25-75 mmol phosphate daily. Phosphate metabolism was previously shown to be disturbed in patients with severe burns, and hypophosphatemia has been reported to disturb oxygen transport by reducing synthesis of 2,3-DPG in the red cells. In this study, S-P was decreased in the first post-trauma week because of a negative phosphate balance the first 4 post-trauma days, but 2,3-DPG remained at normal concentrations. These findings indicate that post-traumatic disturbance in red-cell phosphate metabolism may be prevented by administration of phosphate and that such supplementation is important in the metabolic management of severely injured patients.