We investigated the positive rate of specific IgE to various allergens in 548 patients with allergic rhinitis who visited 13 hospitals in Hokkaido in 2001. House dust and mite were most common allergen in our study. On the other hand, the positive rate for pollens were in the order of birch, timothy, orchard grass, and mugwort. In comparison with past study, the positive rate to birch had increased and the positive rate to timothy and orchard grass had decreased. The positive rate of specific IgE to birch was higher in Asahikawa, its neighborhood, and Sapporo, while Kushiro, Tomakomai, Wakkanai, and Nemuro lie on the coast were lower region. These findings suggested that the positive rate of specific IgE to birch varies in different region even in the same island, Hokkaido and might be influenced by climate.