Amino acids are an essential part of parenteral nutrition. This study aimed to determine the serum profile of amino acids and their loss in urine in patients with long-term home parenteral nutrition (HPN) during 12 h of infusion in comparison with similar parameters in the remaining 12 has well as in healthy participants. We enrolled forty-five patients with long-term HPN for 6-75 (median, 33) months. The indication for HPN was short bowel syndrome secondary to radical resection of the small intestine following complications of Crohn's disease. HPN was administered via two-chamber all-in-one bags prepared in a hospital pharmacy overnight for 12 h each day. The average dose of amino acids, carbohydrates and fats administered was 1.5, 3.4 and 0.68 g/kg per d, respectively, at an infusion rate of 0.11, 0.28 and 0.06 g/kg per h, respectively. The levels of essential amino acids in the serum of the patients were not significantly different from those in healthy individuals; however, of the non-essential amino acids, cystine and glutamine levels were lower and glycine and ornithine levels were higher in the patients (P < 0.05). Excretion of amino acids in the urine during 12 h of infusion at an infusion rate of 0.11 g/kg per h was 301 mg, while it was 104 mg during the remaining 12 h (P < 0.0001). Our patients on long-term HPN had a normal serum profile of essential amino acids. The total urinary excretion of amino acids during 12 h of infusion accounted for only 0.34 % (0-23-0.46) of the administered dose.