Serum IgA antibodies to three Aspergillus fumigatus antigen fractions were determined by enzyme-linked immunosorbent assay (ELISA) in 13 patients with aspergilloma, 23 patients with aspergillus lung infiltrates, 8 patients with allergic broncho-pulmonary aspergillosis (ABPA), and 113 healthy blood donors. All three groups of patients had higher median serum IgA antibody levels against the three antigen fractions than healthy subjects. Thirty six (82%) of 44 patients had IgA antibody values to at least one antigen fraction above the 95 percentile of the blood donor group. Patients with aspergillomas and aspergillus lung infiltrates had slightly higher IgA antibody levels than ABPA patients. Determination of serum IgA antibodies to A. fumigatus antigen fractions had a lower diagnostic efficacy than previously found for IgG antibodies.