Aneurysms of the pulmonary artery are very rare pathological vascular conditions. Peripheral pulmonary aneurysms have been reported only in a few cases. The causes of these aneurysms include extensive degenerative changes, traumas, infection and congenital malformations. Because of the imminent danger of rupture, surgical treatment should always be preferred. The following case report demonstrates one of a multitude of possible misdiagnoses for rupture of a pulmonary aneurysm.