The results of a laboratory investigation on the leaching behaviour of wood treated with creosote and of untreated wood are reported. A special leaching test derived from the German standard method DEV S4 test (DIN 38414) has been developed. Samples were leached in deionized water, in a solution buffered at pH 4.7 and in a solution of humic substances. The organic fraction of the leachate was extracted using liquid-liquid extraction. The extracts were analysed qualitatively with GC/MSD and quantified with GC/FID. The results were compared with those of Soxhlet-extracts from creosote-treated wood.