Interferon alpha (IFN α)-based treatment of chronic hepatitis C viral (HCV) infection may induce pulmonary and extrapulmonary sarcoidosis. We report a case of a 50-year-old male patient who suffered from hepatitis C-induced liver cirrhosis with respiratory insufficiency due to severe hepatopulmonary syndrome. After 9 months of treatment with IFNα and ribavirin, he developed an asymptomatic, clinically occult pulmonary granulomatosis, which was not detectable in CT. The diagnosis was made by bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy. The condition did not progress to clinically apparent disease despite continuation of IFN alpha treatment.