Ocular allergy elicits several symptoms, such as itching, lacrimation and redness. Especially, pollen allergy-induced ocular itching is a severe clinical problem; frequent scratching or rubbing of itchy eyes may lead to cataracts. Therefore, the control of the allergy-derived itching is important. Histamine is the crucial mediator of itching in type 1 allergy. However, H₁ histamine receptor antagonists do not inhibit completely pollen allergy-induced ocular itching. Histamine receptors have four subtypes (H_1~H₄ histamine receptor). Therefore, in the present study, we investigated the role of histamine receptor subtypes on pollen allergy-induced ocular itching in mice. Mice were immunized by the repeated ragweed pollen (RP) with adjuvant, and given a subconjunctival injection of RP extract (RPE) into the palpebra for allergic challenge. RPE-induced ocular itching was inhibited by H₁, H₂ and H₄ receptor antagonists, but not H₃ receptor antagonist. The mRNA expression level of H_1~H₄ receptors in trigeminal ganglion and the ocular skin including the conjunctiva was not altered between RP-sensitized and non-sensitized mice. These results suggested that H₁, H₂ and H₄ receptor are involved in pollen allergy-induced ocular itching.