Aloe arborescens Mill., family Asphodelaceae, is a pharmacopoeial plant, the raw material of which is used for the production of medicinal products for various therapeutic uses. The standardization of Aloe species in accordance with the requirements of the British, Japanese, European Pharmacopoeias and the United States Pharmacopoeia is carried out according to the barbaloin content by the spectrophotometric method. The methods are multistage, provide for preliminary acid hydrolysis in combination with the oxidation, liquid-liquid extraction of the formed aglycones and subsequent complexation with magnesium acetate. A mixture of isomers of aloin A and aloin B (barbaloin) and aloenin were isolated by chromatographic methods. It was determined that in all electronic spectra of the extracts and preparations from the leaves of Aloe arborescens Mill., a bathochromic shift of the long-wavelength band in the alkaline-ammonia solution is observed, which confirms the presence of anthracene derivatives. Under conditions of differential absorption, a maximum absorption is observed in the range of 412–416 nm, which indicates the advisability of using barbaloin in the analysis method, which has a maximum absorption at a wavelength of 412 nm. As a result of the study, there were developed methods for the quantitative determination of the total of anthracene derivatives in leaves and preparations of Aloe arborescens Mill. by using of the differential spectrophotometry calculated on barbaloin at an analytical wavelength of 412 nm. The content of total anthracene derivatives calculated on barbaloin was 0.60±0.03% in Aloe arborescens fresh leaves, 0.5±0.02% in freshly prepared juice, 0.135±0.006% in "Aloe juice" and 0.020±0.001% in "Aloe liquid extract", solution for subcutaneous administration, produced by ZAO "Vifitech" and OAO "Dalkhimpharm".