Pulmonary arteriovenous fistula is a congenital vascular malformation originated from abnormalities of capillary development. Fistulas may develop only in the lung or may be associated with similar abnormalities of the skin, mucous membrane, and the other organs. It may occur with hereditary hemorrhagic telangietasia[Rendu-Osier-Weber syndrome]. Recently we have experienced a case of the pulmonary arteriovenous fistula associated with Schwannoma in 20 year old male man. Tennis ball sized bright reddish mass which was composed of variable sized vascular channels filled with blood clots was located in the just subpleural portion of left lower lobe. Left lower lobectomy was done. Microscopic findings showed variable sized numerous blood vessels embedding in the parenchyma. There was a thumb-tip sized brown nodular mass which was turned out to be Schwannoma at the left 7th thoracic paravertebral area.