Ketotifen, a benzocycloheptathiophene, has an orally effective antiallergic as well as antihistaminic properties. In pervious studies, Ketotifen has shown encouraging results on patient with allergic rhinitis, either perennial or seasonal. 39 patients with allergic rhinitis had been treated with Ketotifen 1 mg twice daily for 8 weeks. And we obtained following results. 1) The efficacy rate in sneezing attack was 73.5%, in nasal discharge 71%, in nasal obstruction 58%. 2) Some improvements in at least one of three-major symptoms were noted within 1 week in 30.7%, within 2 weeks in 55.8%, within 3 weeks in 66.7%, within 8 weeks in 87.2%. 3) Physical findings such as colour, swelling of turbinate, character of rhinorrhea were not improved significantly. 4) Side effect was observed only in one patient with abdominal pain and diarrhea, which was subsided after interruption of administration. These results suggested that Ketotifen was effective in treatment of allergic rhinitis.