Measuring soil bulk density (?b) is a complex and time consuming activity. With the development of pedotransfer functions (PTFs) this information can be assessed from other soil parameters which are much easier and faster to measure or are already present in databases. If the function is developed for the soil at a particular parent rock, the estimate may be more accurate. In the development of PTFs to estimate the ?b of the mineral part of the soil, specifically the hard carbonate parent rock material in Slovenia the data, which was obtained in 2006 in the framework of the BioSoil project was used. The data was collected from 15 sample plots which are part of the 16 x 16 km bio-indication network of Slovenia. The data on the concentration of organic carbon explained 89% of the variability of ?b in the mineral part of the soil. If the data on cation exchange capacity was included, the model explainedalmost 94% of the variability of ?b in the mineral part of the soil. A study of the types of sub-horizons was used to estimate the ?b of the organic part of the soil. The data explained 42% of the variability of ?b of the organic part of the soil. The correlation between the growing stock and soil carbon pool was examined. No proof of correlation for the studied plots existed.