Invasive pulmonary aspergillosis is a rare and fatal complication in patients with cystic fibrosis (CF) who lack concomitant risk factors. The few documented cases in children have all resulted in deaths during hospitalisation. We present the case of a 12-year-old boy with CF who was admitted for an exacerbation which was unresponsive to antibiotic therapy. The findings on imaging raised concerns about a possible fungal infection. As a result, voriconazole therapy was started prior to his respiratory deterioration. He was later found to be β-D glucan and Aspergillus Ag galactomannan positive confirming the suspicion for invasive pulmonary aspergillosis. Three months after diagnosis, he was discharged home under stable condition. Voriconazole was continued beyond discharge and resulted in improvement of respiratory symptoms. This underscores the importance of early treatment of pulmonary aspergillosis in patients with CF. Unfortunately, the patient died 6 months after diagnosis from a CF exacerbation.