Mouse models have provided an essential platform to investigate facets of human diseases, from etiology, diagnosis, and prognosis, to potential treatments. Muscular dystrophy (MD) is the most common human genetic disease occurring in approximately 1 in 2500 births. The mdx mouse, which is dystrophin-deficient, has long been used to model this disease. However, this mouse strain displays a rather mild disease course compared to human patients. The mdx mice have been bred to additional genetically engineered mice to worsen the disease. Alternatively, other genes which cause human MD have been genetically disrupted in mice. We are now comparing disease progression from one of these alternative gene disruptions, the γ-sarcoglycan null mouse Sgcg(-/-) on the DBA2/J background, to the mdx mouse line. This paper aims to assess the time-course severity of the disease in the mouse models and determine which is best for MD research. The Sgcg(-/-) mice have a more severe phenotype than the mdx mice. Muscle function was assessed by plethysmography and echocardiography. Histologically the Sgcg(-/-) mice displayed increased fibrosis and variable fiber size. By quantitative Evan's blue dye uptake and hydroxyproline content two key disease determinants, membrane permeability and fibrosis respectively, were also proven worse in the Sgcg(-/-) mice.