Peritoneal carcinomatosis represents regional spread of gastrointestinal, gynecological and other malignancies with or without evidence of systemic metastases. The authors reviewed the natural history and the different types of peritoneal carcinomatosis. A new treatment approach that combines cytoreductive surgery and intraperitoneal chemotherapy is described. The principles of this surgery and the pharmacology principles of intraperitoneal drug administration are explained. The major attraction of intraperitoneal therapy is that following intracavitary drug administration, the peritoneal cavity is exposed to higher concentrations than the rest of the body. A total of 100 patients with peritoneal carcinomatosis followed from one to ten years were treated by this approach. Patients were divided into four prognostic groups according to the histologic findings, extent of diseases, distant metastases and the completeness of cytoreductive surgery. This new cytoreductive approach is particularly effective for patients with low-grade malignancies confined to the abdominal cavity and who had a complete cytoreductive surgery.