Introduction Herbs continue to represent the main sources of raw materials used in various industries such as the pharmaceutical products, food, cosmetics, agrochemicals, etc. Intensive exploration of natural resources, including medicinal plants, uncontrolled management of harvesting, along with environmental and geopolitical instability, conducted to exhaustion of the natural habitats of medicinal plants and reduction of the biodiversity. In order to reduce the pressure of these adverse factors, particularly promising results could be expected from larger use of the biotechnological methods [1]. In recent decades the vast investigations were carried out for assessing the possibility of using the cells and plant tissues cultures as an alternative means for obtaining the natural pharmaceutical products. Plant explants, cultivated in vitro, represents a biological model, which offers the opportunity to study the mechanisms of cells dedifferentiation and differentiation, cells interactions and morphogenesis under controlled conditions. These approaches are with perspectives for determining the factors that regulated plants growth and development. The aim of this study was the study of the effects of natural growth regulators Reglalg on the growth and development of Rhodiola rosea L. callus. Material and methods Cultivation of R. rosea callus in vitro. Stable callus culture was initiated from R. rosea leaves by using the Murashige-Skoog (MS) nutrient medium. The nutrient medium with pH value adjusted to 5.8 and autoclaved (121°C, 22 min) were supplimented with natural growth regulator Reglalg in different dilutions (1/200; 1/400, 1/800 şi 1/1000) and kinetics of biomass accumulation was appreciated. For this callus the biomass accumulation was monitorised in every 5 days, during of 40 days. At each term, from each experimental variant, 3-4 vases were taken for analysis. Results and discussions The pronounced benefi cial effects of Reglalg were observed at dilution 1/1000 at all terms of observations. At lower dilutions of Reglalg, initially the inhibition of cells proliferation dominated. With increasing the duration of cultivation the degree of inhibition decreased, the fact that demonstrate the “adaptation” of callus cells to the presence of active components of Reglalg. The dilution 1/1000 conducted to highest biomass accumulation, compared to the control (without Reglalg in cultivation medium), throughout all period of cultivation. The experiments with inclusion, or exclusion, of phytohormons and Reglalg in the MS cultivation medium demonstrated that Reglalg can not substitute the main growth regulators (6-benzyladenine and α-naphthalene acetic acid), characteristics for this cultivation medium. At the same time, the introduction of Reglalg in the main nutritive medium essentially stimulates the cells proliferation and callus biomass accumulation. Conclusions The callus biomass accumulation is proportional with the increasing deggree of Reglalg dellutions. The highest biomass was recorded in the nutritiv medium with 1/1000 Reglalg dellution. Reglalg application stimulates the process of callus growth and development.