Forensic biological samples often contain small quantities of DNA in presence of mixture of DNA amplification inhibitors. During the genomic DNA extraction, parts of the substrate, as potential inhibitors, could be co-extracted with genomic DNA and reduce or completely disable amplification of microsatellite loci. Aim of this study is to eliminate inhibitors of DNA amplification using activated carbon, without significant loss of human DNA. Quality of extracted DNA was tested by amplification of ten microsatellite loci. In this doctoral thesis, efficiency of non-affinity DNA extraction methods (Chelex and organic extraction) as well as purification methods based on ultrafiltration (Amicon commercial column) and adsorption (activated carbon) were compared. Generally, Chelex extraction method was more efficient, while no statistically significant difference was obtained if purification methods were compared. Application of activated carbon was shown as simple, fast, economic and reproducible purification method. Activated carbon effectively adsorbed hematin, as inhibitor naturally originated from blood, without significant loss of DNA. In addition, concentration of inhibitors present in the substrate, such as humic substances in soil substrate, as well as tannins in wood, was reduced. Amicon was more efficient method for elimination of indigo dye as inhibitor present in denim substrate. Since purification of biological samples based solely on chemical and physical characteristics of activated carbon has not yet been performed, results of this research provide the first insight into a new application of this well known adsobent.