Intraoperative hyperthermic intraperitoneal chemotherapy (HIPEC), used at the time of cytoreduction, destroys cancer cells, especially in cases with multiple millimetric tumor deposits that can not be resected by surgery. This prevents recurrence at a later date, but it can also interfere with the normal surgical wound healing. In this paper, we report two gastrointestinal fistula cases that occured after HIPEC. Oncology specialists should keep in mind that gastrointestinal fistula may occur after HIPEC and multiple reoperations may be required for the appropriate treatment of this condition.