Solid-phase extraction using strong anion exchange disks was evaluated as an alternative extraction method to conventional liquid-liquid extraction (LLE) for the quantitative analysis of the herbicide Dacthal (DCPA) and its mono-and dicarboxylic acid metabolites in ground water. The average recoveries of DCPA and its acid metabolites from deionized water were 93.7 & 2.6% and 85.6 f 2.5%, respectively. The detection limit of the SAX disk method is 0.05 pg/L for a 100 mL water sample. While no DCPA was detected in ground water from the Malheur River Basin in eastern Oregon, the total concentrations of the acid metabolites of DCPA in 100 mL samples of ground water ranged from less than the detection limit (0.05 to 158.2 pg/L and were in good agreement with those determined by means of conventional LLE.