Abstract: Reagent is offered for the determining of the ethanol and method of determining the presence of ethanol in the human body by the method of processing of the biological material by the reagent, composed from the component 1, presenting itself as 0.06-0.36M of solution of sodium dichromate in water, and componet 2--concentrated sulphuric acid; during this biological material is added to the component 1, in the type of preferable saliva, soon after, component 2 is added with proportionate number of the components in volume 0.02-0.12:1:0.25-0.9. Mix and incubate in the period of 1.5-3 min. and determine the presence and quantity of the contained ethanol by the changing of the color carrier, saturated with liquid 3-10% solution of sodium nitroprissidi, 1-5% water solution of gelatine and 10-30% solution of morpholine in water, containing 1-20% multi-atom alcohol, under the effect of developing vapors, during the oxidation of the biological material.