Nephropathic cystinosis is a hereditary disorder characterized by a specific defect in the transport of cystine across the lysosomal membrane, leading to an accumulation of protein-free cystine in tissues, including conjunctiva, liver, bone marrow and kidney. Renal transplantation is necessary because of renal failure. With improved life-expectancy, neurological complications have been reported, including cases of distal myopathy diagnosed ante- and post-mortem. We report on two further rare cases of two siblings suffering from cystinosis who developed a predominantly distal myopathy, proven electrophysiologically and on biopsy during life. The reported clinical picture of a distal atrophy resembling a neurogenic disease, confirms a picture apparently typical in cystinosis. Possible effects of cysteamine therapy on the course of the myopathy are discussed. Copyright 1998 Lippincott Williams & Wilkins