Oximes such as pralidoxime (2‐PAM), obidoxime (Obi), and HI‐6 are the only currently available therapeutic agents to reactivate inhibited acetylcholinesterase (AChE) in case of intoxications with organophosphorus (OP) compounds. However, each oxime has characteristic agent‐dependent reactivating efficacy, and therefore the combined administration of complementary oximes might be a promising approach to improve therapy. Accordingly, a new high‐performance liquid chromatography method with diode‐array detection (HPLC‐DAD) was developed and validated allowing for simultaneous or single quantification of 2‐PAM, Obi, and HI‐6 in human plasma. Plasma was precipitated using 5% w/v aqueous zinc sulfate solution and subsequently acetonitrile yielding high recoveries of 94.2%–101.0%. An Atlantis T3 column (150 × 2.1mm I.D., 3 μm) was used for chromatographic separation with a total run time of 15 min. Quantification was possible without interferences within a linear range from 0.12 to 120 μg/mL for all oximes. Excellent intra‐day (accuracy 91.7%–98.6%, precision 0.5%–4.4%) and inter‐day characteristics (accuracy 89.4%–97.4%, precision 0.4%–2.2%) as well as good ruggedness were found. Oximes in processed samples were stable for at least 12 h in the autosampler at 15°C as well as in human plasma for at least four freeze–thaw cycles. Finally, the method was applied to plasma samples of a clinical case of pesticide poisoning.