Physiologic and biochemical studies have suggested that the inherited disorders cystinuria, Liddle's syndrome, and perhaps Bartter syndrome all result from defects in renal tubular transport processes. With the recent isolation of several candidate transporter genes, these clinically based hypotheses have begun to be confirmed at a molecular level. In addition, the cloning of the water-channel family of proteins has facilitated the characterization of a second gene defect in congenital nephrogenic diabetes insipidus. This review integrates the pathophysiology of these inherited renal tubular disorders with recent molecular genetic discoveries, and provides a starting point for unraveling their pathogenesis at the molecular level.