Aspergillus fumigatus is the causative agent of differents pathologies in the human being: aspergilloma, allergic bronchopulmonary aspergillosis, chronic necrotizing aspergillosis and invasive aspergillosis. In chronic necrotizing aspergillosis there is local invasion of the lung tissue and parenchyma destruction. Chronic necrotizing aspergillosis is different from invasive aspergillosis, because the abscence of vascular invasion or dissemination. Chronic necrotizing aspergillosis is seen in middle-aged and elderly with underlying lung diseases: COPD, tuberculosis sequelae, lung resection, pneumoconiosis, radiotherapy, lung infarction or sarcoidosis. Clinical manifestations are non specific, being the most usual fever, cough, sputum production and weight loss. Incidence of chronic necrotizing aspergillosis is unknown in Chile. Chronic necrotizing aspergillosis can produce death. It requires early diagnosis and treatment. In a patient with a predisposing disease and with prolonged fever and consuntive status, diagnosis of chronic necrotizing aspergillosis should be considered. We present a patient with chronic necrotizing aspergillosis attended at Instituto Nacional del Tórax (Thorax National Institute) in Santiago