AbstractA high‐performance liquid chromatographic (HPLC) analytical method is described for the quantification of the (R)‐ and (S)‐enantiomers of ketorolac when present together in human plasma. The method involves derivatization with thionyl chloride/(S)‐1‐phenylethylamine and subsequent reversed‐phase chromatography of the diastereomeric (S)‐1‐phenylethylamides of (R)‐ and (S)‐ketorolac. The method is suitable for the analysis of large numbers of plasma samples and has been applied in this report to a pharmacokinetic study of ketorolac enantiomers upon intramuscular administration of racemic drug to a human subject. The limit of quantification for each enantiomer of ketorolac is 50 ng/ml (signal‐to‐noise ratio>10).