Postoperative enteral nutrition is a widely accepted route of application for nutrition formulas due to a low complication rate, a good acceptance by patients. and a favorable cost-effectiveness. We report three cases of bezoar ileus after early postoperative enteral nutrition, using a fine needle jejunostomy (FNJ) in two cases and a nasoduodenal tube in one case. A male patient who underwent gastric resection for a gastrointestinal stroma tumor and was nourished through an fine needle jejunostomy developed an acute abdomen on the seventh postoperative day. Surgical exploration revealed a mechanical ileus caused by denaturated nutrition formula distal to the catheter tip. The second case, a female patient, underwent gastric resection for a gastric cancer and on the fourth postoperative day developed acute onset of abdominal pain. Intraoperative findings were the same as described in the first case. The third case, a male patient with necrotizing cholecystitis, underwent open cholecystectomy. Postoperative enteral feeding was performed using a nasoduodenal tube. He developed a small bowel obstruction on the 17th postoperative day that was caused by an intraluminal bezoar. In conclusion, bezoar formation represents an underestimated complication of postoperative enteral feeding. Acute onset of abdominal pain and the development of small bowel obstruction are the main clinical symptoms of this severe complication. The pathogenesis of bezoar formation remains unclear.