Intraperitoneal carcinomatosis accounts for 25~35% of recurrences of colorectal cancer, and peritoneal carcinomatosis from colorectal cancer has been regarded as a lethal condition. However, a combination of aggressive cytoreductive surgery and intraperitoneal chemotherapy has been tried and appears to be beneficial in selected patients. The primary goal of cytoreductive surgery is to remove all visible tumor within the peritoneal cavity. The goal of intraperitoneal chemotherapy is to eradicate the microscopic residual tumor and to prevent its recurrence. There are various ways to perform intraperitoneal chemotherapy. One is postoperative intraperitoneal chemotherapy, and another is intraoperative hyperthermic chemotherapy during surgery. Hyperthermia increases the penetration of chemotherapy into tissues and the level of chemotherapy cytotoxicity. The timing of surgery in cases of intraperitoneal chemotherapy and the optimal dosage of drugs must be evaluated in further studies. In colorectal cancer, the peritoneum should be regarded as an intra-abdominal organ, like the liver. Therefore, intraperitoneal carcinomatosis must be treated by using a combination of aggressive surgical treatment and intraperitoneal chemotherapy. Eventually, the long-term overall survival will be increased.