The management of retroperitoneal hematomas remains confusing to many surgeons because the available literature frequently groups patients with blunt and penetrating etiologies together. Because the underlying injuries and their treatment may differ considerably, the nonoperative or operative approach to the common hematomas is based on mechanism of injury coupled with hemodynamic status of the patient and extent of associated injuries. After blunt trauma, selected retroperitoneal hematomas in the lateral perirenal and pelvic areas do not require operation and should not be opened if discovered at operation. Midline, lateral paraduodenal, lateral pericolonic not associated with pelvic, and portal hematomas are opened after proximal vascular control has been obtained, if appropriate. Retrohepatic hematomas without obvious active hemorrhage are not opened. After penetrating trauma, most retroperitoneal hematomas are still opened. Exceptions include isolated lateral perirenal hematomas that have been carefully staged by CT and some lateral pericolonic hematomas. As with blunt trauma, retrohepatic hematomas without obvious active hemorrhage are not opened.