In skeletal muscles of patients with Duchenne muscular dystrophy (DMD), the absence of dystrophin was thought to lead to the large reduction in all of the dystrophin-associated proteins (DAPs). Of the seven types of DAPs identified in skeletal muscle, only the 43-kDa glycoprotein (beta-dystroglycan) has recently been found in the monkey brain. To clarify the distribution and characterization of dystrophin and beta-dystroglycan in the brain of humans, we carried out immunostaining and immunoblotting studies on tissues from three DMD patients with intellectual disturbances (ages 17,22, and 26 years) and in five controls (age range, 42-74 years). An antidystrophin antibody revealed dystrophin to be localized in neuronal cells and in the vascular wall in control brains, but it was absent from these tissues in DMD patients. In contrast, beta-dystroglycan was distributed throughout neuronal cells and in the vascular wall of control brains, and was well preserved in the brain of patients with DMD.