Pulmonary actinomycosis is a chronic pulmonary infection caused by Actinomyces, a Gram-positive, microaerophilic bacterium. Pulmonary involvement, other than cervicofacially or abdominopelvically, is uncommon and often leads to a misdiagnosis of pulmonary tuberculosis or lung cancer. In order to investigate the clinical, radiological, diagnostic and therapeutic characteristics of pulmonary actinomycosis, we reviewed a total of 25 cases reported in Korea. Thirteen were diagnosed at our hospital between 1985 and 1997 and 12 were reported in Korean publications. The condition occurred most frequently in middle-aged males, the most common symptom being haemoptysis, followed by cough and sputum. The main radiological features were peripherally located mass or nodule and consolidation, with central low attenuation. Complications such as empyema, sinus fistula or mediastinitis did not occur. Diagnosis was confirmed by percutaneous needle aspiration (n = 8), bronchoscopic biopsy (n = 3) or thoracotomy (n = 13). Eleven of 25 cases were treated medically and in nine others, surgical resection was followed by treatment with antibiotics. In conclusion, when a middle-aged male patient presents with haemoptysis and cough, together with radiologic findings of a peripheral mass or nodule with/without central low attenuation, pulmonary actinomycosis should be suspected.