Pulmonary arteriovenous fistula is not a rare congenital malformation, but obviously most often it is a very late diagnosis. Moreover the disease is associated with a high risk of serious complications, namely cerebrovascular accidents. Two patients, an one month old infant and an 8 years old boy with typical symptoms and signs are presented. Both of them were operated upon successfully. It is concluded, that the diagnosis of solitary pulmonary arteriovenous fistula should lead to immediate operation, which is technically easy and of low risk only, even in infancy. Conservative surgery is recommended without sacrifice of healthy lung tissue, i.e. local excision or segmental resection in subpleural lesions and lobectomy for deep-seated fistulas.