Cystinosis is an autosomal recessive disorder characterized by an accumulation of the amino acid cystine in lysosomes throughout the body. The disease is caused by mutations in the CTNS gene (17p13.2) encoding lysosomal cystine-proton co-transporter cystinosin. Patients with the most common and severe infantile form of cystinosis (MIM #219800) manifest during the first year of life with failure to thrive, dehydration or rickets due to renal Fanconi syndrome. The diagnosis of cystinosis is based on measuring elevated cystine levels in peripheral white blood cells or on detecting bi-allelic mutations in the CTNS gene. Corneal cystine crystals causing photophobia are pathognomonic for the disease and are detected in all patients starting from 1.5 years. Despite treatment, cystinosis patients develop end stage kidney disease. Longer survival of patients with cystinosis due to the advances of renal replacement therapy revealed extra-renal organ involvement including retina, thyroid, pancreas, gonads, central nervous system and muscles. The cystine depleting drug cysteamine dramatically improved renal and extra-renal organ survival in cystinosis and remains the cornerstone of the therapy. The drug should be administered promptly after making the diagnosis and continued life-long, while awaiting new potentially curative therapies that are currently being investigated.