The impact of introduced (cherry laurel, black pine) and indigenous (oak-hornbeam, spruce, yew) trees on soil organic matter (SOM) characteristics(total, labile and hot water soluble carbon, total nitrogen content -NT, and humus quality)in Arboretum Mlyňany, Slovakia, was studied. Original growth was oak-hornbeam forest the rest of which was chosen as a control. The results showed thatintroduced and indigenous trees distinctly influenced SOM quantity and quality in A horizons. The most influenced parameters were labile and non-labile carbon, lability, humus substances C, fulvic acids C, and the least NT content.