Disease progression and efficacy of fungistatic treatment in pulmonary aspergilloma (PA) are difficult to monitor. The usefulness of chest tomography, IgG-ELISA serology, double immunodiffusion, and IgG-immunoblotting was assessed in monitoring disease progression and efficacy of itraconazole treatment during a 9-yr follow-up of a patient with two exacerbations of PA. A rise in IgG-ELISA titer coincided with a recrudescence of clinical symptoms, whereas a decrease after treatment paralleled clinical improvement. IgG-binding to a 32-kD serine protease and to 60- and 94-kD proteins produced with collagen-containing culture medium closely corresponded with IgG-ELISA titers. IgG-binding to a 40-kD metalloprotease remained at very low levels until symptoms and fungal growth became well advanced, when a sharp rise was seen. Responses to all antigens rapidly diminished after the start of successful treatment with itraconazole. Serology may be a useful adjunct in the monitoring of disease progression and the efficacy of itraconazole treatment in patients with PA. IgG-binding to individual fungal proteins shows subtle differences in kinetics. Immunologic responses to fungal proteases raised with collagen-containing culture media may reflect fungal proteolytic involvement during disease progression and treatment more closely than responses to proteins raised with conventional media.