Onobrychis viciifolia is a valuable fodder plant in the Legume family (Fabaceae), which is fed to the animals fresh, as hay or as pickled fodder. It is an excellent nectar source, with the flowering stage lasting for 23-27, which makes it possible to obtain up to 300 kg/ha honey [3, 5]. This species is cultivated in Europe, Asia and North America as forage leguminous crop [1]. It is perennial, polycarpic and reproduces exclusively by seeds [4]. Worldwide, there are about 100 species of the genus Onobrychis, but the wild flora of the R. Moldova includes only four species of sainfoin. Common sainfoin – O. viciifolia var. communis (which can be harvested once a year), O. viciifolia var. bifera (bigger plants, which can be harvested twice a year) and O. arenaria (Kit.) DC are more popular due to their value as forage and melliferous plants [2].  The biometric study was based on a set of indices (plant height, number and size of leaves, number and size of inflorescences) of O. viciifolia plants from the collection of NBGI, grown on the experimental plots of the Plant Resources Laboratory. The stems of plants are erect, branched and fistulous. The leaves are imparipinnate, with elliptical to elongated-obovate leaflets. The fruits are monospermic, indehiscent, semicircular pods. The height of plants in May varies from 75 to 112 cm, lateral shoots start developing from the nodes 3, 4 and 5. There are 2-3 small imparipinnate leaves on each ramification. Every plant has about 21-43 shoots. There are 10-13 leaves on a shoot and they are 12-16 cm long. The number of leaflets varies depending on the position of the leaves on the stem. The leaves at the base are smaller than the others and they have fewer leaflets – by 2-3 pairs, on mature leaves there are 10-12 pairs of leaflets. The leaflets are 1.3-2.8 cm long and 0.4-0.6 cm wide. Smaller leaves, bearing 3(4) pairs of leaflets, grow at the axil of the leaves, at the base of the stem.   At the end of May, on a shoot, there are 3-6 inflorescences, 6-9 cm long. At their base, up to 10 flowers are open, the rest are floral buds. The inflorescences are racemes, with pink-lilac flowers.  In June, plant height is about 95-118 cm. The number of shoots increases as new shoots of smaller diameter develop from the base of the stems. Lateral shoots, bearing 2-3 leaves, grow from each node of the stem. Some leaves, at the base, wither and fall off, but the petiole remains attached to the stem. The leaves grow larger (14-16 cm long, 4-6 cm wide), the number of leaflets on the old leaves remains the same. Inflorescences become longer (8-18 cm). At the same time, in the upper part of the inflorescences, there are floral buds, in the middle – flowers and at the base, green-coloured fruits start developing. The research on the biological characteristics of plant growth and development as well as the biometric study allow identifying important biological features of plants, such as the production of green mass, highlighting the value of the studied species as a fodder crop.