A 64-year-old man was admitted to our hospital with multiple brain abscesses accompanied by pulmonary arteriovenous fistula (PAVF). He had been diagnosed with PAVF eight years previously, but had refused any treatment despite a developing exertional dyspnea. Rendu-Osler-Weber disease was diagnosed as well because the patient exhibited teleangiectasis of the nasopharyngeal mucosa and persistent gastro-intestinal bleeding. Despite administration of antibiotics and corticosteroids the abscesses perforated into the lateral ventricle. The natural history of this rare disease is still incompletely understood. Thus, the time at which treatment should be commenced remains unclear. However the natural course of PAVF is unsatisfactory, and it appears that treatment by surgery and/or embolization should be considered in all cases.