Labile fractions of organic matter can rapidly respond to changes in soil and they have been suggested as sensitive indicators of soil organic matter. Two labile fractions of organic carbon in the soils amended with fresh municipal sewage sludge in two rates (equivalent of 60 kg P ha-1 and 120 kg P ha-1) were studied. Soils under studies were overgrown with Salix in Germany, Estonia and Poland. In Polish soils application of sewage sludge increased the content of both labile organic carbon fractions (KMnO4-C and HWC) for a period of one year. Estonian soils were stable and no distinct changes in labile organic carbon fractions occurred.