An analytical method has been developed to quantitate diethyldithiocarbamate (DDTC) in plasma by derivatization and HPLC analysis. A plasma sample is rapidly derivatized by addition of 10 ul of Meerwein's reagent (Et3O+BF4−) in methylene chloride. The resulting S-ethyl diethyldithiocarbamate is extracted into chloroform containing S-isopropyl diethyldithiocarbamate as the internal standard. Concentrations of DDTC are then determined by reverse phase HPLC analysis with detection at 254 nm. The detection limit for DDTC as the S-ethyl ester is 5 ng/ml. The chromatographic response is linear over the range of 250 to 500,000 2 ng/ml (R2< 0.9995). This method has been used to determine DDTC plasma levels in animal models prior to clinical use of DDTC as a kidney rescue agent for patients receivingcis-diamminedichloroplatinum(II) (Cisplatin) chemotherapy.