The inwardly rectifying K⁺ channel KCNJ10 is mainly expressed in the brain, the inner ear, the retina, and the kidney. Analysis of KCNJ10 knockout mice (KCNJ10-/-) has evidenced the important role of this K⁺ channel in the central nervous system, the eye, and the inner ear. This study aimed at investigating the localization of KCNJ10 in the kidney of C57BL6 mice. In immunofluorescence experiments we observed KCNJ10-specific staining in distal convoluted tubules, connecting tubules, and early cortical collecting ducts. Intercalated cells in connecting tubules and collecting ducts exhibited none or only weak staining. The tubular segment proximal of the macula densa, i.e. cortical thick ascending limb of Henle's loop, was negative for KCNJ10. The staining was restricted to the basolateral membrane compartment including the invaginations of the plasma membrane which also show strong staining for the Na⁺/K⁺-ATPase. The localization of KCNJ10 suggests that this channel plays a role for providing the driving force for electrogenic transport, e.g. Na⁺/Ca²⁺-exchanger or Cl^- channels, and for K⁺ recycling across the basolateral membrane. Therefore, KCNJ10 might be of importance for the so-called pump-leak coupling in renal distal tubules.