Specific IgG and IgG(4) antibodies against Canadida albicans were exmined in 48 healthy and 69 asthmatic subjects to analyze the mechanism causing an increased production of these immunoglobulins. 1. The level of C.albicans-specific IgG and IgG(4) antibodies was higher, not significantly in IgG(4), in asthmatics under 30 years of age, compared with healthy subjects of the same age group. 2. Specific IgG and IgG(4) antibody levels in both healthy and asthmatic subjects showed a tendency to increase with aging, and significant difference was present between cases under 30 years and cases over 70 years of age. 3. Any difference in the production of specific IgG and IgG(4) was not observed in elderly cases older than 60 years between healthy and asthmatic subjects.