A correlation between serum levels of IgE and IgG, was examined in 79 patients with bronchial asthma. High levels of IgG₄ were not always correlated to high levels of IgE in all subjects with asthma. IgG₄ levels tended to increase as IgE levels increased in patients over age 60, but not in those under age 59. The results show that serum IgG₄ levels are associated with serum IgE levels in patients over age 60 and are related to patient age in all subjects with asthma.