Vascular complications are rare in cases of simple anterior dislocation of the shoulder but the axillary artery or its branches may be damaged. Very few cases are found in the literature reporting false aneurysms of axillary artery secondary to blunt trauma to the shoulder. A case of pseudoaneurysm of the axillary artery in a 75-year-old woman is reported. Diagnosis was suspected because large pectoral haematoma with haemodynamic instability appeared a few hours later after manual reduction of the dislocation. The pseudoaneurysm was confirmed with selective angiography of the axillary artery. Arteriography should be performed whenever vascular injury is suspected. Delayed recognition of these lesions may lead to permanent neurologic deficits despite adequate vascular repair of the axillary artery. A coordinated vascular and orthopaedic approach and prompt surgical treatment may assure full upper limb function. Although endovascular treatment of these lesions could seem attractive, we prefer to use open surgical techniques because they allow us to treat frequent concomitant injuries and perform decompression of the axillar fossa because of the large haematoma.