1. 1. Glycosaminoglycans were isolated from vitreous and aqueous humors of the trout using a purification technique of cetyl pyridinium chloride complexing followed by analysis of hexuronic acid. 2. 2. Aqueous humor contains 0·017 ± 0·003 mg/ml and vitreous humor 0·011 ± 0·001 mg/ml hexuronic acid. 3. 3. High concentrations of soluble protein normally present in teleost ocular fluids result in incorrent estimates of hexuronic acid. 4. 4. Treatment of ocular tumors with hyaluronidase significantly reduces the glycosaminoglycan content.