Consumption of tea has been shown to inhibit the growth of several tumour types in animals, including cancers of the lung and oesophagus^,,. Drinking tea, especially green tea, is also associated with a lower incidence of human cancer. The mechanisms of cancer inhibition are not known, although several hypotheses have been proposed. We investigated whether drinking green tea could suppress angiogenesis, a process of blood-vessel growth required for tumour growth and metastasis. We find that green tea, and one of its components, epigallocatechin-3-gallate (EGCG), significantly prevents the growth of new blood vessels in animals. This finding indicates that drinking tea may be beneficial for the prevention and treatment of angiogenesis-dependent diseases, including cancer and blindness caused by diabetes.