In patients who have been the victims of high-energy trauma, severe pelvic injury should always be suspected. Most of these fractures are stable and respond well to conservative treatment. Pelvic fractures constitute 3% of all skeletal fractures and are associated with high-energy trauma. They are potentially serious injuries with significant mortality and large numbers of associated lesions. There are fundamentally three sources of bleeding in pelvic fractures: arterial, venous and through the bone ends of the fracture. Arterial bleeding is more associated with hemodynamic instability. In such cases, both early external fixation of the pelvic fracture and angiography with selective embolization of the bleeding vessels are effective methods for achieving hemostasis. Aneurysms of iliac artery branches are rare and are mostly pseudoaneurysm relating to the traumatic event. The natural history of pseudoaneurysms is unknown because of their rarity, but if they rupture, the mortality rate is high. We report a case of spontaneous thrombosis of a pseudoaneurysm of a branch of the right iliac artery.