Following the death of a patient with propionic acidaemia with a cardiomyopathy we reviewed 19 patients with the same disorder for evidence of cardiomyopathy. Six patients were found to meet the diagnostic criteria. Three patients died and in the other three the cardiac disease resolved completely. All patients were treated with standard therapy and some received L-carnitine but this did not seem to influence the eventual outcome. Cardiomyopathy is an important complication of propionic acidaemia and may be rapidly fatal.