Toxocara canis is nematode parasite of dogs. Children are particularly subject to infestation, however the larva remains quiescent at stage II. Toxocara can localize in the eye and induce a variety of clinical manifestations. A case of ocular toxocara is presented in which there was granulomatous endophthalmitis. Immunologic testing was negative in the serum but positive in the vitreous, where numerous eosinophils and plasma cells where found. Vitreous and aqueous IgE levels were elevated. Corticosteroid therapy was ineffective in quieting the inflammation, but vitrectomy was beneficial. Biological testing demonstrated the advantages of using specific antigens with ELISA techniques. Negative test results in the serum do not obviate the need to perform assays of the aqueous and/or vitreous. The demonstration of an eosinophilic inflammatory response and elevated IgE levels support the diagnosis of ocular parasite infection. In the absence of specific anti-parasite therapy corticosteroid treatment appears to yield inconsistent results. Vitrectomy seems to be beneficial in these circumstances. The new diagnostic technique should improve the accuracy of ocular toxocara diagnoses.