The set of procedures of doxylamine quantitative determination in blood by the method of high-performance liquid chromatography using amphiphylic solvents (isopropanol, acetonitrile, methanol) under the conditions of aqueous phase saturation by ammonium sulphate has been developed; acetonitrile application in the weak-acid medium (рН = 5) is optimal. Validation of the developed procedures has been carried out in the variant of the method of standard and the possibility of application of the method of standard for determination has been shown with the purpose of rationalization of quantitative determinations carrying out in forensic toxicology.