AbstractCountercurrent chromatography (CCC) has been successfully applied for the separation of four chlorinated s-triazine derivatives, namely, simazine, atrazine, propazine, and trietazine, which are widely used as herbicides. Of several solvent systems investigated, n-hexane-ethyl acetate-methanol-water (8:2:5:5) gave the best range of the partition coefficient values because of the satisfactory solubility for all samples and therefore was used for the separation of s-triazines. Two types of countercurrent chromatographs, high speed CCC, and horizontal flow-through coil planet centrifuge, were used for s-triazines separation, and the identity of the separated fractions was unequivocally established by mass spectrometry. The potential practical application of CCC to herbicide analysis is discussed.