The article presents a clinical case of hypersensitivity pneumonitis complicated by a viral infection in a 72-year-old woman. The introductory part provides a concise literature review on the etiology, classification, frequency, and possible complications of hypersensitivity pneumonitis. The patient’s computed tomography (CT) lung scan showed bilateral interstitial lesions. The patient was diagnosed with idiopathic pulmonary fibrosis based on the clinical manifestations and radiological findings. The autopsy revealed morphological signs of hypersensitivity pneumonitis (obliterative bronchiolitis, moderate interstitial fibrosis with honey-combing, nonspecific interstitial pneumonia, giant multinucleated cells) and viral lung damage (exudative stage of acute respiratory distress syndrome with interalveolar edema, hyaline membranes lining the alveoli, pneumocyte desquamation, and ugly giant cells). Keywords: hypersensitivity pneumonitis, exogenous allergic alveolitis, viral infection, lungs