We present the case of an otherwise healthy 41-year-old woman, who was admitted after having expectorated bright red blood. While the chest roentgenogram was found to be normal, fiberoptic bronchoscopy revealed mild active bleeding originating from the apicoposterior segmental bronchus of the left upper lobe, which exacerbated during the examination. The bleeding was contained through blockade of the upper lobe bronchus by means of a double-lumen endotracheal tube. After the patient had been referred to our department, we performed a resection of the superior segmental group of the left upper lobe. The histopathological examination of the specimen revealed a malformation of the bronchial artery with an abnormal communication to a branch of the pulmonary artery. The malformation was located in close proximity to the apicoposterior segmental bronchus. Whereas arteriovenous malformations with a pulmonary artery branch as feeding vessel have been described in more than 500 cases and primarily affect patients with hereditary hemorrhagic teleangiectasia (HHT, Rendu-Osler-Weber disease), the 23 reported cases of malformations supplied by a branch of the bronchial artery show no evidence of heredity. Furthermore, clinical appearence and localisation show characteristical differences between arteriovenous malformations with pulmonary arterial supply and malformations arising from a bronchial arterial source. Therefore, it seems appropriate to make a clear-cut distinction between these two patterns of vascular malformation of the lung.