This is a case of 52 years old male patient with chronic obstructive pulmonary disease (COPD) who developed semi-invasive pulmonary aspergillosis while on pegylated-interferon alpha-2a and for chronic hepatitis C infection. This complication is very rarely seen during interferon therapy for other any purposes. Pulmonary aspergillosis in particular group of chronic hepatitis C patients under immunosupressive therapy should also be in mind and interdisciplinary medical cooperation might be needed during the treatment for immune-suppressed patients. Pulmonary aspergillosis is also discussed from many aspects in the light of the literature.