AIM:To study the distribution of Urotensin-Ⅱ(U-Ⅱ),a new biological activity substance in tissues of human eye.METHODS:The different tissues of normal fresh human eye were separated and homogenized,then the distributions of U-Ⅱ were measured by radio-immuno-assay.RESULTS:There were distributions of U-Ⅱ in any tissues of human eye,ranging 0.807-32.958ng/g.The U-Ⅱ content in optic nerve was the highest(32.958±1.741ng/g),then sclera,iris,cornea,ciliary body,choroid,retina and lens in turn.The U-Ⅱ content in vitreous body and aqueous humor were the lowest.The U-Ⅱ content in optic nerve was 40.4 times of that in aqueous humor.CONCLUSION:U-Ⅱ is distributed in tissues of human eye widely.Its effects of physiology and pathophysiology need to further study.