A procedure has been developed for the determination of eight organophosphorus insecticides in natural waters by use of stir-bar-sorptive extraction (SESE) combined with thermal desorption-GC-atomic emission detection (AED). Optimization of the extraction and thermal desorption conditions showed that an extraction time of 50 min and a desorption time of 6 min were sufficient. Addition of salt and adjustment of the pH were not necessary Recoveries of seven of the compounds investigated were between 62% and 88%. For fenamiphos, which is highly water-soluble, recovery was only 15%. The very low limits of detection, between 0.8 ng L-1 (ethion) and 15.4 ng L-1 (fenamiphos) indicate that the SBSE-GC-AED procedure is suitable for sensitive detection of OPP in natural waters. The procedure was evaluated with real water samples.