Myostatin is a member of the TGF-beta superfamily of secreted growth factors. A lack of functional myostatin or inhibition of the normal myostatin function results in an increased muscling phenotype and, conversely, the systemic administration of myostatin results in muscle wasting. Thus, myostatin is well established as a negative regulator of skeletal muscle mass. Myostatin binds to cell-surface receptors to inhibit both the proliferation and differentiation of myoblasts. Moreover, it functions to regulate both embryonic and post-natal musculature. Thus, potential antagonists to myostatin, whether targeting myostatin synthesis, secretion or receptor binding, show great promise as therapies against muscle-wasting diseases. This review provides an expert opinion on the biology and potential of myostatin antagonists in the treatment of muscle-wasting disorders.