Rhabdomyolysis is a syndrome characterized by injure of skeletal muscle with the release of intracellular constituents into the circulation. Acute renal failure is a common complication and is the leading cause of morbidity and mortality in these patients. The most common aetiology is traumatisms, muscle compressions and extreme exertions. Most commonly, the cause of rhabdomyolysis is evident from the careful clinical history. Nevertheless, when the precipitant is not obvious the diagnosis is difficult and a raised clinical suspicion is required. We should investigate used medication or drugs, infections, electrolyte abnormalities and a number of inherited enzyme deficiencies, in which cases the muscle is unable to use available energy. We report two clinical cases of acute renal failure due to rhabdomyolysis by metabolic myopathies due to a carnitine palmitoyltransferase deficiency on the one hand and by myophosphorylase deficiency on the other. We describe their clinical features and progress.