We report a case of a 30-year-old man with infantile form cystinosis , an autosomal recessive lysosomal storage disease, who presents with three years of progressive arm weakness and dysphagia without dyspnea, dysarthria, or weakness in the lower extremities. There is no family history of similar symptoms. Examination demonstrated flaccid weakness in the bilateral upper extremities, which progressed to complete weakness over the course of subsequent clinic visits, areflexia in the upper extremities, without prominent fasciculations, bulbar weakness, pseudobulbar affect, or pathological reflexes. Serum and CSF studies for inflammatory, infectious, autoimmune, and paraneoplastic factors were negative, and brain and spinal cord imaging studies were unremarkable. NCS/EMG demonstrated chronic neurogenic changes as well as fibrillations/positive sharp waves and fasciculations throughout muscles of the right lower extremity and thoracic paraspinal muscles. A sural nerve biopsy demonstrated rare crystals in the nerve periphery but no crystalloid infiltration of the nerve itself. As the life expectancy for patients with cystinosis continues to increase and patients survive into adulthood, late onset complications are becoming more apparent. Neurological sequelae of cystinosis have been described, including myopathy, chiari malformations, and idiopathic intracranial hypertension. [JNI5] We propose that patients with cystinosis can develop motor neuron disease as a late-onset complication. This case demonstrates that motor neuron disease should be considered in the differential diagnosis for patients with cystinosis who develop weakness.