Myostatin is a member of the TGF-β family of signaling molecules that appears to act as a negative regulator of skeletal muscle growth. In the November 28 Nature Bogdanovitch et al. demonstrate that inhibition of myostatin could be used as a therapeutic approach to increase muscle mass and treat myopathy diseases (Nature 2002, 420:418-421). Antibodies against myostatin were tested in the mdx mouse model of Duchenne muscular dystrophy (DMD). The treated mice gained weight and displayed increased muscle mass and caloric output. The treatment caused a functional improvement of the dystrophic phenotype, suggesting that similar pharmacological strategies targeting myostatin might be applied to treat human muscular diseases and offer an alternative to gene therapy.