The absorption spectra of the solutions of vitamin substances were analyzed, on the basis of which molar absorption coefficients of vitamins were calculated by the Bouguer-Lambert-Ber law. The abundances of components (mol/dm3) were defined in treble Multivitamins as a result of solving a system of linear algebraic equations with the use of the computed molar coefficients of light absorption in the solutions of vitamins В2, В6, В9. Results are obtained with an accuracy of 4%, which made in mass terms 0.04-0.10 mg.