A 77-year-old woman with rectal cancer and synchronous liver metastasis underwent a Hartmann operation with D3 lymph node dissection in June 2014. mFOLFOX6 plus bevacizumab(bev)was then administered to treat the liver metastasis.In February 2015, multiple liver metastases were detected and the regimen was changed to FOLFIRI plus bev.After 3 courses, peritonitis due to intestinal perforation around the descending colostomy occurred, and an emergency operation(partial resection of the descending colon and transverse colostomy)was performed.FOLFIRI was then administered from 2 months after the operation.After 3 courses of this regimen, a CT scan showed progression of the hepatic metastases.The regimen was therefore changed to mFOLFOX6.Five months later, another CT scan showed an intestinal perforation of the transverse colostomy at the abdominal wall, and an emergency cecostomy was performed.At this stage, chemotherapy was ceased.This case highlights the risk of intestinal perforation during chemotherapy, regardless of the use of bev.