We investigated the effect of long-term ethanol intake on the function of skeletal muscle mitochondria from 30 human alcoholics. Mitochondrial studies included (1) oxidative phosphorylation, (2) the activity of the individual complexes of the respiratory chain, and (3) the cytochrome content. State 3 and state 4 oxidation rates with glutamate-malate, succinate, tetramethyl-p-phenylenediamine-ascorbate, and acetylcarnitine-malate, the activity of the individual complexes of the respiratory chain, and the concentration of mitochondrial cytochromes were comparable in control subjects and alcoholic patients, and also in myopathic and nonmyopathic alcoholic patients. These results demonstrate that alcoholic myopathy is not associated with a deficiency in mitochondrial energy supply.