The mechanisms involved in the renal excretion of quinolone and new quinolone antibacterial drugs are still incompletely understood. The purpose of this study was to examine the renal handling of nalidixic acid (NA) and enoxacin (ENX), using the renal cortical slices uptake techniques in rats. It was demonstrated that both NA and ENX were taken against a concentration gradient by a saturable processes resulting from the ratio of slice to medium (ratio of S/M) being dependent on the time and the concentration. It was indicated that the inhibition of uptake by 2,4-dinitrophenol, ouabain and sodium cyanate was shown to be an energy dependence. Probenecid and cimetidine exhibited that they might inhibit NA uptake slightly. ENX uptake was inhibited by probenecid, cimetidine, guanidine and disopyramide, suggesting that ENX might possess an affinity for both anionic and cationic transport mechanisms.