Spirulina platensis is a cyanobacterium that has been largely studied due to its commercial importance as a source of protein, vitamins, essential amino acids, and fatty acids [5]. Photosynthesizing microorganisms, like Spirulina platensis, can be an alternative source of proteins for food and feed purposes. Also, there is the possibility of obtaining pigments such as carotenoids, phycocyanin and chlorophyll [7]. The use of the Spirulina sp. for pigments as colorant has already been explored by the cosmetic, pharmaceutical and food industries. Phycobiliproteins are brilliantly colored, highly fluorescent, water-soluble protein components of Spirulina platensis. Recent studies have demonstrated the antioxidant [6, 3], hepatoprotective [9], and anti-inflamatory [9, 8, 4] properties of C-phycocyanin, represents one of the main group algae’s peptides. The present work aimed to study the influence additional concentration of sodium chloride on concentration of phycocyanin, extracted from Spirulina platensis, cultivated on pure and filtration media. One part of Spirulina platensis was grown on pure media, second part was cultivated on the filtration Zarrouk’s medium [11]. Cultivation was carried out in 150 ml culture vessel, with 2-2.5 klux light intensity at constant temperature 29±10C during 13 days. On second day of cultivation was added 0.4M and 0.5M NaCl, at that moment on second and fourth days was added 0.4M and 0.5M NaCl partially. The biomass was washed once with water and collected. Then obtained biomass subjected to freeze-thaw through 10-14 days. Samples centrifugated (6000 rpm) and supernatant, contains phycocyanin, was collected and extracted by water. Control probe represents the highest concentration of phycocyanin [2, 10] during almost all days. First’s days of cultivation show the small concentration of phycocynin, because addition the NaCl is a stress factor for algae. The best concentration of phycocyanin in sample with addition NaCl during cultivation is 0.4M NaCl, added partially to biomass, and up to 22.5% (0.2+0.2M NaCl , 11th day), in control probe it is about 15%. Further concentration of phycocyanin in biomass of Spirulina platensis is growing first 10-11 days, then it falling down in all probes (Fig. 1).Cultivation on the old media gives less content of phycocyanin in biomass. The best concentration of phycocyanin in sample with addition NaCl during cultivation is 0.5M NaCl, added partially to biomass, and up to 22.4% (0.25+0.25M NaCl , 12th day), in control probe it is about 22% (7th day). Also the increased concentration of NaCl during cultivation of Spirulina platensis has no big influence on growing of phycocyanin (Fig. 2). Fig.2. Concentration of phycocyanin, extracted from Spirulina platensis, during 13 days of cultivation on a filtration medium Purity of the phycocyanin during 13 days of cultivation reached only 1.7 [1]. That show, that we didn’t get a pure extract of phycocyanin and have to implement some biochemical methods of extraction and purification proteins and peptides.