Organic-geochemical analyses have been applied to seepage water and leakage water samples of a waste deposit landfill in order to give a comprehensive view on the composition of the organic contaminants. Based on intense GC/MS screening analyses a wide variety of organic substances were identified and attributed to natural or xenobiotic waste components. Apart from plant material-derived compounds and degradation products of peptides, carbohydrates and lignin, numerous xenobiotic substances were identified and attributed to the groups of pharmaceuticals, plasticizers, pesticides or chlorinated aromatics. Not all of the substances identified in the seepage water samples were recovered in the leakage water sample due to degradation processes or dilution by uncontaminated water. Quantitative analysis of selected contaminants was used to discriminate substances affected by degradation processes and persistent compounds.