β-Dystroglycan, a 43-kd transmembrane dystrophinassociated glycoprotein, plays an important role in linking dystrophin to the laminin-binding α-dystroglycan. α-/β-Dystroglycan is encoded by a single gene on chromosome 3p21 and ubiquitously expressed in muscle and nonmuscle tissues. No known human diseases have been mapped to this locus. Here, we describe the selective deficiency of β-dystroglycan in a 4-year-old Saudi boy with muscular dystrophy. The patient had a borderline elevation of serum creatine kinase level and early-onset proximal symmetrical muscle weakness and wasting without calf hypertrophy. The milder phenotype may suggest a secondary deficiency of β-dystroglycan; however, the unique immunofluorescence labeling suggests that the patient may present a novel form of muscular dystrophy.