Hypersensitivity pneumonitis (HP; extrinsic allergic alveolitis) is a rare non-immunoglobulin E (IgE)-mediated inflammatory lung disease caused by inhalation exposure (occupational, recreational or ordinary home exposure). A 36-year-old female patient, without significant medical history, is referred to an outpatient pulmonology clinic for dry cough, shortness of breath, fever, fatigue and weight loss. Chest high-resolution computed tomography (HRCT) was performed, and significant lung fibrosis (especially centrilobular and interlobular in bilateral "thick lines"), traction bronchiectasis and alveolitis in both superior lobes are described. Lung function tests showed severe restrictive dysfunction. Transfer factor of the lung for carbon monoxide (TLCO) being very low, the flexible bronchoscopy was contraindicated. Surgical lung biopsy was performed. Histopathological examination showed characteristic lesions of chronic bilateral hypersensitivity pneumonitis. The patient died four days after the surgical intervention due to post-operative complications. Exposure to various chemical substances can form bonds with human proteins molecules and induce an exaggerated immune response in susceptible individuals. A high index of suspicion of occupational exposure can determine an early diagnosis with a better outcome.