A case is reported of lipid storage myopathy in a 24-year-old patient and her family. In the patient and an aunt, muscle biopsy disclosed intrafibrillar lipid depositions, and electron microscopy revealed lipid vesicles in the sarcolemma border. In the father, no lipid depositions were observed but electron microscopy showed alterations to mitochondria compatible with a mitochondrial myopathy. In the patient muscular biochemistry revealed a major reduction in NADH oxydase activity and in the aunt a diminished level of carnitin compatible with carnitin deficiency. The heterogeneity of these lipidic myopathies is discussed.