Contusion or prolonged compression of the buttock produced severe local injury in 3 cases. Rhabdomyolysis with acute renal failure occurred in 2 of these cases, and one of them had an associated sciatic nerve palsy. The affected muscles included the gluteus maximus, gluteus medius, and the tensor fascia latae. Clinically and experimentally, these muscles were shown to be functionally enclosed within separate compartments like the peripheral limb muscles. Prompt decompression in the two cases with pressures exceeding 30 mm Hg resulted in muscle and nerve recovery.