Petersen's hernia after esophagectomy is quite rare. The patient was a 75-year-old man, who had undergone esophagectomy via right thoracotomy and reconstruction with a jejunal loop by the antesternal route in 2014. In March 2015, severe acute abdominal pain occurred after endoscopy. Contrast-enhanced abdominal CT revealed a diffuse low density area in the abdominal cavity and partial dilatation of the small intestine with torsion of the superior mesenteric artery. The patient underwent emergency laparotomy, revealing chyle-like ascites and pallor of almost the entire small intestine due to circulatory impairment because of strangulation after herniation through Petersen's defect. After strangulation was relieved, the color and motility of the small intestine recovered rapidly. Then we closed the defect between the jejunal pedicle and the transverse mesocolon. This is the first English report showing Petersen's hernia after esophagectomy.