Noni juice and a protein-free, alcohol precipitate of Noni juice inhibited angiogenesis in in vitro human angiogenesis models. When growth medium contained Noni juice at least over the range from about 2.5% to about 33% (by volume), angiogenesis was blocked. Moreover, Noni juice and an ethanol precipitate were able to destroy a pre-existing angiogenic response as well as prevent the development of new vessels. Noni juice was effective in inhibiting the growth of angiogenic vessels from breast cancer explants. It will also be effective in treating cancers and non-cancerous diseases whose response includes an increase in angiogenesis, e.g., retinopathy of prematurity, neovascular glaucoma, diabetic retinopathy, and psoriasis. The primary antiangiogenic component is believed to be a carbohydrate with a molecular weight less than about 6000 Daltons. In an initial experiment, oral administration of Noni juice appeared to adversely affect the antioangiogenic component(s) in the juice.