Heredity hypouricemia is caused by renal hypouricemia or by xanthinuria. Here we’re going to discuss about xanthinuria. Xanthinuria divided to type 1 with deficiency of xanthine dehydrogenase, and type 2 with xanthine dehydrogenase and aldehyde oxidase deficiency. Here in we report a case of xanthinuria type 1 that develop with kidney failure, hemodialysis done for him but kidney function not modified, so kidney transplant done for him. His serum uric acid was 0.1 mg/dl before and after transplantation.