Myostatin is a negative regulator of skeletal muscle growth. Myostatin mutations and pharmacological strategies increase muscle mass in vivo, suggesting that myostatin blockade may prove useful in diseases characterized by muscle wasting, such as the muscular dystrophies. We subjected the γ‐sarcoglycan–deficient (Sgcg^−/−) mouse model of limb‐girdle muscular dystrophy (LGMD) 2C to antibody‐mediated myostatin blockade in vivo. Myostatin inhibition led to increased fiber size, muscle mass, and absolute force. However, no clear improvement in muscle histopathology was evident, demonstrating discordance between physiological and histological improvement. These results and previous studies on the dy^w/dy^w mouse model of congenital muscular dystrophy and in the late‐stage δ‐sarcoglycan–deficient (Sgcd^−/−) mouse model of LGMD2F document disease‐specific limitations to therapeutic strategies based on myostatin blockade in the more severe mouse models of different muscular dystrophies. Muscle Nerve, 2007