Skeletal muscle in congestive heart failure is responsible for increased fatigability and decreased exercise capacity. A specific myopathy with increased expression of fast-type myosins, myocyte atrophy, secondary to myocyte apoptosis triggered by high levels of circulating tumor necrosis factor-α (TNF-α) has been described. In an animal model of heart failure, the monocrotaline-treated rat, we have observed an increase of apoptotic skeletal muscle nuclei. Proapoptotic agents, caspase-3 and -9, were increased, as well as serum levels of TNF-α and its second messenger sphingosine. Treatment of rats withl-carnitine, known for its protective effect on muscle metabolism injuries, was found to inhibit caspases and to decrease the levels of TNF-α and sphingosine, as well as the number of apoptotic myonuclei. Staurosporine was used in in vitro experiments to induce apoptosis in skeletal muscle cells in culture. Whenl-carnitine was applied to skeletal muscle cells, before staurosporine treatment, we observed a reduction in apoptosis. These findings show that l-carnitine can prevent apoptosis of skeletal muscles cells and has a role in the treatment of congestive heart failure-associated myopathy.