Our understanding of the effectiveness of early decompressive fasciotomy for acute posttraumatic compartment syndrome is incomplete. Thirty-two patients who developed acute clinically evident compartment syndrome (23 in the leg, 9 in the forearm) were treated with decompressive fasciotomy an average of 16 hours after injury. Thirty patients (94 percent) underwent fasciotomy in conjunction with other urgent operative procedures mandated by concomitant injuries. Three patients required early amputation for a failed arterial repair. Only 2 of 29 patients with limb salvage (7 percent) had postoperative myoneural deficits after decompressive fasciotomy. Both of these patients had preoperative myoneural deficits. Decompressive fasciotomy before the development of ischemic myoneural deficits prevents the ischemic sequelae of acute clinically evident compartment syndrome.