We report 4 cases of gastrointestinal perforation associated with systemic administration of bevacizumab. Case 1: A 51- year-old man with colorectal cancer (CRC) received mFOLFOX+bevacizumab (Bev). A small intestinal perforation occurred 7 days after Bev administration (Bev-a) and was successfully treated with omental packing. Case 2: A 50-year-old woman with CRC received capecitabine+Bev. A small intestinal perforation was detected 5 days after Bev-a, and was successfully treated with primary suture and an omental flap. Case 3: A 74-year-old man with CRC received CapeOX+Bev. A duodenal perforation occurred on the same day as Bev-a, but could be treated conservatively. Case 4: A 57-year-old man with lung cancer received DTX+Bev. A small intestinal perforation occurred 13 days after Bev-a, but this could be managed with primary suture and an omental flap. The gastrointestinal perforation presented with mild abdominal pain and was detected within 14 days after Bev-a in each of these 4 cases. Three patients were successfully treated with only minimal surgical procedures and 1 patient could be managed with conservative treatment for a perforated duodenal ulcer.