The medical records of 31 patients (19 male and 12 female) with clinical and electrophysiologic features of Wohlfart-Kugelberg-Welander syndrome were reviewed. The reported age at onset ranged from less than one year to 46 years, and the age at diagnosis ranged from three to 66 years. Proximal muscle weakness, especially of the lower extremities, and muscular atrophy were the predominant clinical features. Elevated serum creatine kinase levels were noted in four female and 12 male patients, and the degree of elevation was higher in the male patients (up to 32 times the upper limit of normal) than in the female patients. On initial evaluation, two patients were wheelchair-bound, whereas the others were ambulatory. On follow-up evaluation three to 32 years later (mean, 15.5 years), 11 patients used wheelchairs, although only three were wheelchair-bound. The disease followed a steady, slowly progressive course. The outcome of ambulatory status did not correlate with the initial creatine kinase determination.