We examined the potential toxicity of desflurane in 13 young 25.0 +/- 2.3 (mean +/- SD) yr-old men, given 7.35 +/- 0.81 MAC-hours of desflurane anesthesia. Hepatic and renal function tests, serum electrolytes, and standard urine and hematologic tests were performed before, during, and after anesthesia. No toxicity was found. There were no changes in tests of hepatocellular integrity (plasma alanine transferase activity), synthetic function (serum albumin, prothrombin time, partial thromboplastin time), or renal function (serum creatinine concentration, blood urea nitrogen concentration). Decreases in red blood cell count, hematocrit, and blood hemoglobin concentration during and immediately after anesthesia were attributed to blood sampling and infusion of intravenous electrolyte solution. These values returned by 4 days after anesthesia to values not different from those before anesthesia. Increased white blood cell counts and blood glucose concentrations noted during anesthesia with other inhaled anesthetics were also seen in these volunteers. Desflurane appears to have no greater toxicity than currently used inhaled anesthetics and, because of its lesser metabolism, may have lesser or not toxicity.