Intraperitoneal immunotherapy actually is a promising concept for treatment of peritoneal carcinomatosis for several reasons: The use of specifically engineered therapy in terms of antibodies or stimulated T lymphocytes against epithelial tumour antigens offers an elegant way to attack tumours on the peritoneal surface, as peritoneal cells have a mesenchymal origin. This is especially true for modern multimodal treatment concepts, were local compartment treatment together with systemic chemotherapy and (if possible) surgical tumour removal will be individually combined.