Limb-girdle muscular dystrophy type 2E (LGMD 2E) is caused by mutations in the β-sarcoglycan gene, which is expressed in skeletal, cardiac, and smooth muscle. β-sarcoglycan-deficient (Sgcb-null) mice developed severe muscular dystrophy and cardiomyopathy with focal areas of necrosis. The sarcoglycan–sarcospan and dystroglycan complexes were disrupted in skeletal, cardiac, and smooth muscle membranes. ε-sarcoglycan was also reduced in membrane preparations of striated and smooth muscle. Loss of the sarcoglycan–sarcospan complex in vascular smooth muscle resulted in vascular irregularities in heart, diaphragm, and kidneys. Further biochemical characterization suggested the presence of a distinct ε-sarcoglycan complex in skeletal muscle that was disrupted in Sgcb-null mice. Thus, perturbation of vascular function together with disruption of the ε-sarcoglycan-containing complex represents a novel mechanism in the pathogenesis of LGMD 2E.