Recent studies underscore the importance of oxygen supply in bladder cancer. Tumour growth stimulates the production of vasoactive factors to increase oxygen delivery to tissues by vasodilatation. Any vasoconstrictor mediator could impair this vasodilatation reducing the oxygen supply. 8-Iso-PGF2 alpha is a potent vasoconstrictor agent. The aim of this work is to determine 8-Iso-PGF2 alpha release in healthy bladder mucosa and in superficial bladder cancer in order to investigate a pathophysiological vasoconstrictor answer of the superficial bladder cancer. The study was conducted on a sample of 12 patients; for every subject studied 8-Iso-PGF2 alpha release was assayed in healthy bladder mucosa and in superficial bladder tumour. 8-Iso-PGF2 alpha release was significantly reduced (p less than 0.001) in superficial bladder cancer compared with healthy bladder mucosa. The inhibition of the production of a powerful vasoconstrictor such as 8-Iso-PGF2 alpha in the vascular homeostatic mechanism of bladder cancer can represent a response of the tumor tending to contrast an antagonist effect of vasodilatation and the necessary to support the oxygen supply.