A long-term follow-up study of patients with familial distal myopathy with rimmed vacuole formation and a review of the literature indicates that the prognosis of the disorder was extremely poor as to daily life. Although the initial symptom appearing in early adulthood was muscular wasting and weakness in the legs, especially the distal muscles, severe generalized skeletal muscle involvement with sparing of the facial, extraocular, bulbar, intercostal and diaphragm muscles was recognized in the advanced stage. The disease is probably inherited as an autosomal recessive trait, while there is a considerable female preponderance, the female-to-male ratio being 2:1. The disorder is distinguishable from various types of distal myopathy on the basis of clinical and pathological findings, and other myopathies with rimmed vacuole formation, including inclusion body myositis, from a prognostic viewpoint.