Blood phosphorus was measured in consecutive 136 admitted patients in the department of general surgery between Oct. 1987 and Jan. 1988. It was found that 32 cases (23.5%) were with hypophosphatemia on perioperative period. Sixteen patients with normal preoperative blood phosphorus level undergoing digestive tract surgery were randomly divided into 3 groups, each was fasted for 7 days postoperation and given different kind of transfusions. Group 1, patients were given 250 g of glucose daily with no phosphorus, blood phosphorus level was significantly decreased. Group 2, 250 g of glucose with 7.5 mmol of phosphate daily, blood phosphorus level decreased slightly on the 2nd-4th day and returned back to normal on day 7. Group 3,500 g of glucose with 15 mmol of phosphate daily, blood phosphorus level decreased moderately on the 2nd-4th day, and returned to normal level on day 7. Perioperative hypophosphatemia was attributed to: (1) Poor absorption or massive loss of phosphorus through digestive tract. (2) Intracellular transferring of blood phosphorus accompanied by the phosphorylation of saccharide. (3) Excessive excretion of phosphorus through urine. The authors suggested that 7-9 mmol of phosphates per 100 kcal daily for the prevention and 7-15 mmol of phosphates per 1000 kcal daily for the treatment of hypophosphatemia.