AbstractThe peritoneal surface remains an important failure site for patients with colorectal cancer. Peritoneal metastases of colorectal cancer are at present considered equal to distant metastatic disease. Consequently, peritoneal carcinomatosis is treated with systemic chemotherapy and surgery only to palliate complications such as obstruction. Despite the development of new chemotherapeutic agents and combinations, the results remain disappointing with a limited impact on survival. Colorectal carcinoma cells are relatively resistant to chemotherapy. Intraperitoneal chemotherapy seems to be an attractive approach in the treatment of high‐risk colorectal cancer and peritoneal carcinomatosis from colorectal origin providing high local drug concentration with limited systemic side effects. Adjuvant early postoperative intraperitoneal chemotherapy is worthwhile for consideration as treatment option after resection of high‐risk colorectal cancer. In the treatment of peritoneal carcinomatosis postoperative intraperitoneal chemotherapy leads to inadequate exposure of the peritoneal surface. Only an intraoperative intraperitoneal chemotherapy performed with direct cytotoxic drugs such as MMC and cisplatin overcome this problem. The limited drug penetration in tissue implies the need for extensive cytoreductive surgery. The results of phase II studies suggest that an increased median survival can be achieved with this approach. The natural history of this disease and the heterogeneity of the patients are such that only a randomized trial design will adequately answer the question whether regional treatment of patients with peritoneal dissemination of colorectal cancer actually prolongs survival. The results of such a study are to be expected in approximately 2 years time. J. Surg. Oncol. 2002;79:46–61. © 2002 Wiley‐Liss, Inc.