A 72-year-old woman who underwent colorectal endoscopy because of positive fecal occult blood test results was diagnosed with ascending colon cancer.Preoperative CT revealed advanced ascending colon cancer and portosystemic shunt between the ileocecal vein and inferior vena cava.It was necessary to cut the shunt when ileocecal resection was performed. The patient had no symptoms caused by the shunt, and blood examination results showed no liver enzyme abnormalities. Abdominal ultrasound examination revealed no liver cirrhosis and normal blood flow in the portal vein and shunt flow from the ileocecal vein to the inferior vena cava.We assessed that surgery could be safely performed without increasing portal vein pressure.Laparoscopic ileocecal resection was performed by cutting the shunt.Partial jejunum resection was also performed for a mesenteric tumor observed intraoperatively, and pathological findings revealed a lymphangioma.The patient was discharged home on postoperative day 7 without any symptoms, liver enzyme abnormalities, or ascites suggestive of increased portal vein pressure on abdominal ultrasound examination.Colorectal cancer surgery with simultaneous cutting of a portosystemic shunt has rarely been reported.It is necessary to consider the causes of portosystemic shunt and then cut the shunt during surgery when needed.