Pulmonary arteriovenous fistulas are rare congenital malformations associated in 40% of cases with Osler-Weber-Rendu disease. PAF acquired in connection with the chest trauma, surgery and some inflammatory or neoplastic lung diseases were also described. In the Institute of Tuberculosis and Chest Diseases we have observed 11 cases of congenital PAF in 4000 resected lungs during the last years. In this report we described one more case with PAF. A 40 years old man was admitted to the Institute of Tuberculosis and Chest Diseases with hemoptysis. History and physical examination was unremarkable. Chest roentgenogram revealed a right upper lobe infiltrate. Tuberculosis or cancer was suspected and during the diagnostic procedures antituberculous drugs were given. After 3 weeks of treatment hemoptysis increased and chest roentgenogram revealed progression of the infiltrate in the right upper lobe and new lesions in the middle lobe. According to the character of X-ray progression which night be characteristic of active bleeding, a possibility of arteriovenous fistulas could not be excluded. As life threatening haemorrhage persisted right upper lobectomy without angiography was done. In the resected lobe arteriovenous fistulas were found. Angiography after operation was proposed but was refused by the patient. He is now well and symptoms free 5 months.