In a screen for naturally occurring angiogenic inhibitors, we have identified an extract from the seed of the plant Livistona chinensis, which has potent anti-angiogenic and anti-tumor activity. The aqueous extract inhibits the in vitro proliferation of endothelial cells and multiple tumor cell lines including mouse fibrosarcoma and human breast and colon cancer. In mouse experiments, this extract suppresses the growth of the subcutaneous fibrosarcoma tumors. When the seed is separated into different components, the shell including the seed skin appears more potent than the inner kernel in tumor suppression. Our results suggest that the extract from the shell of Livistona chinensis may be a potential supplemental source for cancer treatment.