Intravitreal injection of Toxocara canis and Ascaris suum larvae into guinea pigs is being studied as a model for human ocular toxocariasis. IgE antibody-mediated mechanisms may be of importance in the ocular immunopathologic reaction to ascarid parasites. Intravitreal injection of second and fourth stage A. suum larvae, second stage T. canis larvae, or a soluble antigen obtained from cultures in defined media of third stage A. suum molting to the fourth stage (ACF antigen) was followed by the appearance of IgE antibody in aqueous humor and serum, detectable by the 6-day passive cutaneous anaphylactic (P-K) test. Animals systemically immunized to the ACF antigen and possessing serum IgE antibody titers of 1:1,000 to 1:10,000 had little or no IgE antibody in their aqueous humor. The ability of soluble antigens to provoke systemic and intraocular IgE antibody responses suggests that antigens released by living larvae may be important in this process. The observation that intraocular IgE antibodies occur in some animals lacking detectable serum IgE antibody indicates that the intraocular IgE antibody is locally produced.