The serum levels of total IgE, IgG and IgG(4) were compared among five age groups of patients with bronchial asthma. 1. The level of serum IgE was significantly higher in the patients before the age of 29 than in those between the ages of 30 and 49 (p < 0.02), between 50 and 59 (p < 0.01) and between 60 and 69 (p < 0.01). The serum IgE level tended to increase in the patients over age 70. 2. The serum level of total IgG was significantly higher in the patients over age 70 compared with the level in the 30-49 (p < 0.05) and the 60-69 year old groups (p < 0.05). 3. The serum IgG(4) level was increased with aging, although no significant difference was found among the five age groups. 4. The IgG(4) level correlated to a certain extent with the level of serum IgE. The results reveal that the levels of total IgE, IgG and IgG(4) are increased in the elderly patients over age 70, and that there is a relationship between serum levels of total IgE and IgG(4).