Actinomycosis is a chronic suppurative infection characterized by extensive necrosis, fibrosis and sinus formation without regard to normal tissue planes. The causative organism in human infection is Actinomyces israelii. Thoracic actinomycosis is diagnosed in the presence of poor oral hygiene, pulmonary infiltrate, empyema, sinus tract and osteomyelitis of ribs. However, in the absence of chest wall involvement, the diagnosis of pulmonary actinomycosis is difficult and its initial clinical manifestations may lead physicians to suspect tuberculosis or neoplasm. It could not be distinguished from tuberculosis or neoplasm radiologically. We report a case of pulmonary actinomycosis in a 64 year old woman with a review of the literature.