Immunoblotting, radioallergosorbent test (RAST), and enzyme-linked immunosorbent assay (ELISA) were performed to determine specific IgE and IgG responses to Aspergillus fumigatus (Af) allergens (IgE-Af; IgG-Af). Serology results were compared in patients with allergic bronchopulmonary aspergillosis (ABPA) (n = 43), patients with Aspergillus fumigatus-associated asthma (Af-asthma) (n = 26), and healthy individuals (n = 3). In patients with different clinical phases of ABPA, three specific immunopatterns were found by immunoblotting. It is proposed to classify ABPA into the active, intermediate, and remission phase with respect to the specific immunoresponse to Af-allergens and asthma symptoms. First, the active phase of ABPA is characterized by a fully developed specific immunoresponse to Af-allergens and severe asthma. Second, the intermediate phase includes patients with elevated specific immunologic findings without asthma symptoms. Third, the remission phase is characterized by a weak specific immunoresponse to Af-allergens after a long-term asymptomatic period. No correlation occurred between specific immunopatterns and irreversible brochopulmonary lesions. The IgE-Af RAST and IgG-Af ELISA titers of patients with ABPA in the active and intermediate phase were significantly higher compared with patients with ABPA in remission phase and with patients with Af-asthma. In particular, the demonstration of positive IgG-Af ELISA titer generally allows the serologic discrimination of patients with asthma and ABPA from patients with Af-asthma in clinical practice. The present study revealed that immunoblots of most patients with Af-asthma were negative. Immunoblotting demonstrated an IgG reactivity exclusively to low molecular weight (MW) Af-allergens in 8 out of 26 patients with Af-asthma and in the three healthy individuals, and this IgG response may reflect naturally occurring antibodies.