Researches in biotechnology are urgently needed, where a special emphasis occupies the obtaining strains of algae that can be sources of biologically active substances. These microorganisms are used in the microbiological industry for obtaining biologically active substances, such as proteins, lipids carbohydrates, which in turn can be used in the pharmaceutical, cosmetic, animal husbandry or plant cultivation. In this context were obtained pure cultures of Spirulina, Nostoc, Anabaena, Chlorella, Ulva genera etc. Some of them can serve as sources of carbohydrates such as Ulva lactuca or Nostoc linckia species, their biomass containing an impressive amount of the carbohydrate – until 35,27% and 35–50% respectively. Other species are distinguished by high content of proteins such as Spirulina platensis, and some are used as sources of lipid, being a feedstock for the biogas. The results are known, giving a valuable chemical composition of autochthonous species of cyanophyte algae species namely Nostoc flagelliforme, Nostoc gelatinosum and Anabaena propinqua. These species are a promising source of biologically active substances. Protein content of these strains varies between 20% -38% of dry biomass. They have also a significant pigment content which has decisive role in the regulation of metabolic processes and in maintaining the elasticity of the cell membrane. Thus, there is a need to obtain strains of algae with potential for the development of the biotechnology. Within the laboratory “Phycology” of Moldova State University we keep a number of cyanophyte algae including the micro alga – Calothrix elenkinii Kossinsk. – CNMN-CB-14. The strain was isolated in pure culture from the samples of soil collected near the Cimislia, Moldova. To obtain pure algae culture were used methods for repeated cultivation on liquid and agar medium. For growth and development of microalgae can be used Drew mineral medium with the following chemical composition: K2HPO4 – 0,2g/l; MgSO4×7H2O – 0,2 g/l; CaCl2×2H2O – traces; FeCl3 –traces. The medium is prepared on distilled water and the cultivation is carried out with keeping the temperature of + 24 – + 29ºC and lighting of 2000 lx. This strain forms dark brown colonies, has bowed trichomes of asymmetrical shape with the gelatinous sheath. Vegetative cells have various shapes from spherical to cylindrical. Basal cells have a width of 4,0 to 9,0 μ and length from 2,0 to 7,0 μ. Trichomes become narrower toward their ends, cells become cylindrical with width from 2,5 to 5,5 μ. Terminal cell is rounded or slightly sharp. Each trichomes contains one spherical or oval basal heterocyst with 2,0 to 7,0 μ length and 3,0 to 7,7 μ wide. Biochemical analysis have shown that Calothrix elenkinii dry biomass contains 11,9% -13,3% of proteins, 20,0% of lipids, 52,9% – 66,0% of carbohydrates and 1,63 – 1,83% of phycobiliproteins. In conclusion we can state that the microalgal strain Calothrix elenkinii Kossinsk is a promising source of biologically active substances.