By increasing tendency of intoxication with several preparations at a time, there is lack of data in the sources of information about the chemical-toxicological research of the psychotropic drugs in the mixture. The aim of this research was to determine possibility of qualitative analysis of benzodiazepines derivatives--diazepam, flunitrazepam, nitrazepam, oxazepam and tetrazepam in the mixture, extracted from biological fluid (blood). The high performance liquid chromatography was used for the investigation, the reagents--tablets of diazepam, flunitrazepam, nitrazepam, oxazepam and tetrazepam. It was found out that the most acceptable eliuent for the analysis of the mixture by high pressure liquid chromatography is phosphate buffer, containing 0.02 M penthanesulfonic acid:etannitrile (55:45) (pH=3.5). The optimal wavelength for identification of the drugs in the mixture is 254 nm.