Homologous passive anaphylactic reaction mediated by a reaginic antibody was caused in rat conjunctiva and the effects of several drugs on this reaction were examined by estimating the leakage of dye in the tissue as a parameter of the increased vascular permeability during anaphylaxis. In this model, topical application of disodium cromoglycate did not produce any effect, while given intravenously marked inhibition was elicited. Other antiallergic drugs such as dexamethasone, mepyramine, epinephrine and glycyrrhizin were effective topically as well as systemically. On the other hand, indomethacin given orally and topically tended to enhance the reaction. Present results suggest that this model may be useful as a convenient method for screening of topical antiallergic drugs on the immediate ocular hypersensitivity reaction.