In this project, the four Italian Cystic Fibrosis Center enrolled 164 adult patients to conduct sputum and blood tests to diagnose and classify the Aspergillus lung disease. Most of the patients showed chronic infection by Pseudomonas aeruginosa (54.3%), by methicillin susceptible Staphylococcus aureus (MSSA) (43.9%), while a minority of patients showed chronic infection by Alcaligenes xylosoxidans (8.5%), by methicillin-resistant Staphylococcus aureus (MRSA) (7.3%) or by Staphylococcus aureus small colony variant (2.4%). As proposed by the Baxter’s classification to assess the possible degree of aspergillosis, the researchers carried out different tests to detect the Aspergillus infection. Nevertheless, the results of the serological tests (detection of IgG and IgE antibodies) and of the molecular analysis (real-time PCR) proved to be unreliable and have not allowed a correct classification of patients with Aspergillus infection using Baxter’s criteria. The analysis of the potential impact of Aspergillus on lung function indices is currently underway.