Abstract. The analysis of organic matter components was carried out for 3 soil subtypes, identified and diagnosed in Harghita Mountains, namely a Stagnic Luvosol, a Histic and a Histic-Skeletic Prepodzol. The purpose of our research was to identify some qualitative and quantitative differentiations within the organic matter. In this respect, the organic matter accumulation is high and it correlates with altitude and land cover. The lowest degree of humification characterises the stagnic Luvosol, while the highest is present in the histic-scheletic Prepodzol. The polymerization degree of humic acids reveals the dominant formation of fulvic acids (among which, the aggressive fraction dominates in the lower half of the soil profile). The non-extractible fraction has the highest values in the case of the stagnic Luvosol (which does not provide favourable conditions for the development of microbial flora) and the lowest ones in the case of the histic skeletic Prepodzol
