The objective of the present study was the development of the method for the extraction of toxic compounds from the uncoloured hairs with the use of enzymatic hydrolysis by proteolytic enzymes of the toxic compounds comprising the group of pharmaceutical substances present on the uncoloured hairs collected for the forensic medical expertise. The experiments were carried out using laboratory animals, viz. guinea pigs having hair of natural white and black colour and white rats that were given per os a phenobarbital solution and a dimedrol solution as well as daily intravenous injections of tropicamide hydrochloride administered every 28 days. The hair obtained from the experimental animals was subjected to acidic, alkaline, and enzymatic hydrolysis with chymotrypsin, trypsin, and papain. The analysis of the extracted materials was performed using the gas chromatographic technique with mass-selective detection. The results of the study give evidence that the completeness of the extraction of the toxic substances from animal hairs with the use of enzymatic hydrolysis is twice and thrice that of acidic and alkaline hydrolysis respectively. The enzymatic hydrolysis methods developed in the present study are equally efficient using the naturally coloured white and black hairs of the laboratory animals which allows to recommend them for the extraction of poisonous substances from such material. The methods were validated.