Many studies have reported a close association between VEGF and tumor angiogenesis. The aim of the present study was to evaluate the effectiveness of gene therapy against cancer, including peritoneal metastasis, using a cDNA encoding a soluble type of Flt-1, one of the VEGF receptors. In a peritoneal metastasis model of MKN45 human gastric cancer cells, mice repetitively treated with intraperitoneal injections of HVJ-Fex, a type of HVJ-cationic liposome encapsulating a plasmid expressing soluble mFlt-1, exhibited smaller disseminated foci with fewer microvessels, thus resulting in a significantly longer survival period than the control mice. In