In order to perform therapy for carcinomatous peritonitis by a new angiogenesis inhibitor, TNP-470, we investigated the effective timing and the optimal doses for intraperitoneal administration using two mice models. In both carcinomatous peritonitis models caused by M 5076 tumor and B 16 melanoma, the early administration of TNP-470 within one week after tumor inoculation extended the survival times of the mice receiving the drugs, whereas the administration of TNP-470 one week or later after inoculation did not affect the survival time. However, there were significant differences in the effective therapeutic doses of TNP-470 between the two models. It is important to select the best timing and doses for intraperitoneal administration of TNP-470 based on the state of angiogenesis and the sensitivity of the tumor tissues to TNP-470.