Introduction. Chronic necrotizing pulmonary aspergillosis (CNPA) is a cavitary, infectious process of lung parenchyma with slow progressive course. Vascular invasion and dissemination to other organs are unusual. Case report. We presented a 25-year old man with bilineal acute leukaemia who developed pulmonary and systemic symptoms. Chest CT showed nodular consolidations and cavitary lesions in both lungs. Bronchial biopsy revealed necrotic hyphae but it was negative for Aspergillus by culture. Serum was positive for antibodies to Aspergillus, but it was negative for antigens. A thoracoscopic lung biopsy of the upper left lobe revealed necrosis of lung tissue, with acute and chronic inflammation of the cavity wall and the presence of hyphae consistent with Aspergillus species. Conclusion. Although confirmation of the diagnosis is difficult, a combination of characteristic clinical, radiological and histological findings and either serological results positive for Aspergillus or the isolation of Aspergillus from respiratory samples are highly indicative of CNPA.