The paper presents results of research carried out in 2013-2022 within the EU CLIMA EAST Moldova Project and the Research and Innovation Project: 20.80009.7007.01 on the estimation of carbon stock in biomass and soil of grasslands in Orhei National Park (ONP). Grasslands in the Republic of Moldova (RM) are an important source of greenhouse gas (GHG) absorption, as they account for about 27% of the total GHG fluxes in the country. The importance of grasslands is also determined by their share in the land use structure of the RM, where according to the land cadastre they account for 10.7% or 361.1 thousand ha. Current research results from the ONP are used in the process of updating data on carbon stocks in grassland ecosystems in the RM. In this context, by applying the AR-AM0002 methodology on the grassland land within the ONP (about 5.9 thousand ha) a sample of 61 sample plots (SP) was located, of which 27 SP for biomass carbon and 34 SP for soil carbon. According to the research it was established that the grasslands within the ONP grow on 33 taxonomic soil units, of which cernozones predominate with about 33%. Based on the results of the laboratory analyses it was determined that the total amount of carbon stored in the soil pool of the grassland in the ONP is 342.6 ktC or an average of 58.7 tC/ha. At the same time, the min/max values are 33.9 tC/ha and 78.6 tC/ha respectively. Overall, these indicators are characteristic of degraded soils and are relatively similar to the results obtained in the monitoring exercises of Moldova Soil Conservation Project and Moldova Community Forestry Development Project. The biomass of the grasslands within the ONP was estimated by gravimetric or weighing method. Thus, it was determined that the productivity of the grassland sites within the study sample ranged from 1.19-3.97 t/ha aboveground dry mass, with a mean of 2.78 t/ha. The average productivity of the grasslands within the NWP is 2.16 t/ha above-ground dry mass which corresponds to the "medium productivity" classification (1.3-2.5 t/ha dry mass). The cumulative mean value of the biomass of the grasslands (above and below ground) in the ONP is 4.32 t/ha dry mass. Final calculations indicate that the average volume of carbon in biomass in the study sample is 2.16 tC/ha, and the cumulative volume per sample - 12.4 ktC. The results obtained show the urgent need for improvement works on degraded grasslands by applying different methods (fertilization, over-seeding, etc.) and their reasonable management.