We used technetium Tc 99m medronate (methylene diphosphonate) scanning in the treatment of seven patients with rhabdomyolysis. In three patients the intense, diffuse, symmetric nature of the scans was suggestive of an underlying metabolic muscle disorder. The scans defined the extent of the muscle injury in three patients and demonstrated muscle injury that was not initially suspected in two patients. The scan also demonstrated clinically unsuspected metastatic pulmonary and gastric calcifications in one patient. All scans showed evidence of renal dysfunction. In conclusion, these cases demonstrate that Tc 99m medronate scanning helps to define the extent and location of muscle injury in rhabdomyolysis, and that diffuse muscle uptake of Tc 99m medronate may be associated with metabolic muscle disease.