The uric acid peak among the compounds in aqueous humor separated by high pressure liquid chromatography was identified by its retention time, the UV absorbance characteristics, and the effect of uricase. The uric acid concentration in the aqueous humor of normal monkey, human eyes with cataract, and human eyes with glaucoma are<0.05, 1.7±0.3, and 3.8±0.4 respectively. The significance of high uric acid concentration in glaucoma is discussed.