Culture filtrate antigens of Aspergillus fumigatus Ag 534 were purified by preparative isoelectric focusing and affinity chromatography. One of the pooled antigen fractions from the preparative isoelectric focusing step (pool 2) was passed through a concanavalin A column and yielded two components, designated antigens IIa and IIb. Antigen IIb reacted more strongly than antigen IIa with all of the aspergilloma and allergic bronchopulmonary aspergillosis sera tested by enzyme-linked immunosorbent assay. The glycoprotein nature of antigen IIb was shown by the concanavalin A binding properties and staining reactions of the components.