Objective: Ascorbic acid (AA), at physiological concentrations, is a well known anti-oxidant but, at higher concentrations, it can be selectively toxic to cancer cells. Controversial data have shown that administration of intravenous high-dose AA can improve therapeutic outcomes in cancer patients. These effects are thought to occur mainly due to direct cytotoxicity mediated by generation of reactive oxygen species. The anti-tumour effects of AA can also be due to inhibition of angiogenesis, however, this has been poorly studied. This study aimed to investigate the effect of AA on prostate cancer cells and angiogenesis.