A statistical investigation was carried out into about 3, 000 patients who visited our department from 1977 to 1983. The results were as follows:
1. Allergic rhinitis and bronchial asthma were the most important allergic diseases in the rural area.
2. The number of patients with allergic rhinitis especially caused by pollen (so called “pollinosis”) was markedly increased in recent years.
3. Japanese cedar, orchard grass and mugwort were the most important causative agents of pollinosis in this area.
4. The number of patients of each pollinosis was largely changed by climate or other unknown factors in each year.
5. The number of patients of bronchial asthma caused by molds' spores gradually decreased.
6. An occupational pear and apple pollinosis caused by artificial pollination was considered to be the most inportant allergic disease due to farm work. Further investigations are required on this problem.