The lithium disposition to cerebrospinal fluid (CSF) was evaluated in rats with acute renal failure (ARF) to examine whether electrolyte homeostasis of the CSF is perturbed by kidney dysfunction. In addition, the effects of renal failure on choroid plexial expressions of the Na+-K+-2Cl- co-transporter (NKCC1) and Na+/H+ exchanger (NHE1) were also studied.