Renal tubular disorders include various clinical conditions wherein the renal tubular reabsorption of an ion or organic solute is significantly decreased. It may concern the renal handling of a single substance, such as glucose or phosphate, a group of substances or a combination of ions and organic substances. Close to this group of diseases, it is also possible to consider two conditions due to renal tubular resistance to vasopressin and parathyroid hormone: congenital nephrogenic diabetes insipidus and pseudohypoparathyroidisms, respectively. Clinically, the urinary loss of these substances may be inapparent, like in familial glucosuria, but in most cases, it may be responsible for characteristic disorders such as failure to thrive, dehydration, rickets, etc. Recently, physiological and molecular cloning studies have brought crucial information for testing candidate genes and understanding the underlying molecular bases of these disorders.