This is a case report of 53 year old male who underwent pancreatoduodenectomy for chronic pancreatitis. Two months after the operation the symptoms of severe malnutrition caused by nutrition digestive disorders developed. The patient was admitted to the hospital with the symptoms of severe malnutrition and general poor medical condition. The patient was put on total parenteral nutrition (TPN) after the preliminary treatment of water-electrolytes imbalance. After 3 days of TPN a severe hypophosphatemia occurred (serum level < or = 0.25 mmol/l). The refeeding syndrome developed despite the use of phosphate supplementation in the hypocaloric TPN regimen. The hypophosphatemia caused the life threatening neurological and cardiovascular symptoms. The patient was put on intensive infusion fluid therapy with phosphate supplementation and transient withdrawal of TPN, which resulted in the patient's recovery. This case confirms the risk of development of refeeding syndrome in the malnourished patients. It indicates the need of close monitoring of phosphate serum level and the need of phosphate supplementation especially during the first days of nutritional treatment in such patients.