Summary Because the kidney receives a large blood supply and because of its function to concentrate substances in the tubular fluid, there is always the potential susceptibility for nephrotoxicty by even small amounts of toxins. Anesthetics can cause both direct and indirect renal effects. The direct effects seem to be limited to fluoride toxicity most epitomized by methoxyflurane, which is no longer used. The present day agents more commonly used, eg, halothane, enflurane, isoflurane, and the more recently introduced desflurane and sevoflurane, which have some potential for fluoride toxicity, but do not appear to cause significant renal toxicity except in extreme conditions. The indirect effects of anesthetics are of more importance. These effects are hemodynamic alterations, sympathetic activation and humoral regulatory changes. Many of these effects are mitigated when patients' preoperative anxiety is ameliorated, preoperative hydration is maximized, and their medical condition(s) is (are) well compensated. Even with controlled hypotension, the renal effects are usually transitory when the practitioner has a good understanding of the anesthetic agents used, the need for optimal hydration, and how to anticipate and modify the effects of clinical hemodynamics and surgical stress