Introduction.The work is devoted to the development of an analytical approach to determining the concentration of a next generation of VLP-based vaccines using an innovative method based on the kinetics of diffuse reflection (DRf) in optically turbid media. The quality assessment of the latest VLP-based vaccines containing immunological triterpene hydrocarbon adjuvants is of great importance for the effectiveness of immunobiological products. The aim is to develop a new analytical approach based on the kinetics of light reflection in an optically heterogeneous medium for the quantitative determination of VLP vaccines. Materials and Methods. Sample vaccine (Gam-VLP-Rota) for the prevention of rotavirus infection (160 mg/dose). Solutions (140–360 mg/ml) of bovine serum albumin (BSA, 98%) as the model sample. Squalene adjuvant («oil-in-water» type), phosphate buffer solution (1:1) as the dissolution medium. Laboratory setup for DRf from a rough surface of a heterogeneous solution, consisting of an IR-diode emitter, aimed at a cuvette with a sample, a CC-Device designed to convert an optical image into an electrical signal, and the original Soft (Vidan®) for chemometric processing of the analogue signal.Results. The descriptor sd₂ was selected, demonstrating a linear relationship in the coordinates «family of chemometric descriptors (di) — BSA concentration (C, μg/ml)». A calibration line (y = 4,88∙x - 9,83, r=0.9998) was constructed in the coordinates «sd₂-C, μg/ml». The DRf measurements of the VLP-Rota vaccine sample were performed under conditions for BSA solutions (n=9). The concentration C_practical of the tested vaccine sample was determined, based on the sd₂ obtained value. The method was validated in accordance with ICH Q2 (R1) guidelines, confirming linearity, accuracy (RSD< 5%) and repeatability (n = 9, P = 0.95). The repeatability error (ε) was determined to be 9.34%, indicating acceptable intra-assay variation.Conclusion. The proposed DRf method confirms its reliability in routine determination of the concentration of new-generation vaccines.