A number of ion channels and transporters are expressed in both, the inner ear and the kidney. In the inner ear, K⁺ cycling and endolymphatic K⁺, Na⁺, Ca²⁺ and pH homeostasis are critical for normal organ function. Ion channels and transporters involved in K⁺ cycling include K⁺ channels, Na⁺,2Cl^-, K⁺ cotransporter, the Na⁺/K⁺ ATPase, Cl^- channels, connexins and KCl cotransporters. Further, endolymphatic Na⁺ and Ca²⁺ homeostasis depends on the Ca²⁺ ATPase, Ca²⁺ channels, Na⁺ channels and a purinergic receptor channel. Endolymphatic pH homeostasis involves H⁺ ATPase and Cl^-/HCO₃^- exchangers including pendrin. Defective connexins (GJA1, GJB6), pendrin (SLC26A4), K⁺ channels (KCNJ10, KCNQ1, KCNE1, KCNMA1), Na⁺,2Cl^-, K⁺ cotransporter (SLC12A2), KCl cotransporters (KCC3, KCC4), Cl^- channels (BSND, CLCNKA+CLCNKB) and H⁺ ATPase (ATP6V1B1, ATPV0A4) cause hearing loss. All these channels and transporters are also expressed in the kidney and support renal tubular transport or signaling. The hearing loss may thus be paralleled by various renal phenotypes including subtle decrease of proximal Na⁺ coupled transport (KCNE1/KCNQ1), impaired K⁺-secretion (KCNMA1), limited HCO₃^- elimination (SLC26A4), NaCl wasting (BSND, CLCNKB), renal tubular acidosis (ATP6V1B1, ATPV0A4, KCC4) or impaired urinary concentration (CLCNKA). Thus, defects of channels and transporters expressed in the kidney and the inner ear result in simultaneous dysfunctions of these seemingly unrelated organs.