1. Three new cases of injury to main arteries at orthopaedic operations are described, and a follow-up of two previously described cases is given. The rarity of these accidents is a credit to those engaged in orthopaedic surgery, for many orthopaedic operations are done very close to great vessels, and often under the bloodless conditions of a tourniquet. Nevertheless, it is well to have the risk of great vessel injury in mind because such an accident, although rare, may be a serious threat to life or limb.

2. It is important to repair the damaged artery rather than ligate it because the risk to the growth or viability of the limb is lessened.

3. The aim should be a return to full function with as near normal a vascular anatomy as possible.

1. Three cases of severe retroperitoneal haemorrhage complicating fractures of the pelvis are described. In two patients haemorrhage was immediately controlled by ligation of the internal iliac artery. The third patient died before the bleeding could be controlled.

2. Ligature of the internal iliac artery may be a life-saving measure when fracture of the pelvis is complicated by severe haemorrhage.