The main purpose of this research was to monitor the influence of the powdered Cyanobacterium Spirulina platensis addition to plain yoghurt and the yoghurt containing Lactobacillus acidophilus on survival of the microbiota during the refrigerated storage. The cell viability of yoghurt starter cultures (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus) and Lactobacillus acidophilus under refrigeration conditions in yoghurts prepared with (0.5 or 1.0 (w/w) %) and without the addition of Spirulina powder was investigated. The yoghurts were prepared under hygienic laboratory conditions and their pH and acidity were controlled during the process. The samples of yoghurts were stored at 4 degrees C and investigated on days 1, 5, 10, 15, 20, 25 and 30. Viable counts of the lactic acid bacteria were above 6 cfu g(-1) of all "spirulina powder" added samples whereas control yoghurt samples contained lower lactic acid bacteria count at the end of the storage period. Addition of 1 % Spirulina platensis powder into the yoghurts did not cause significant differences on the viable lactic acid bacteria (p <= 0.05). The results showed the positive effect of S. platensis powder on the survival of the lactic acid bacteria during storage of yoghurt (P <= 0.05). The sensory analysis was also performed for the yoghurt samples. Sensory scores of 0.5 % spirulina powder added yoghurt samples were better than 1 % spirulina powder added ones. It was determined that spirulina powder added yoghurt is a good medium of lactic acid bacteria during the 30 days of refrigerated storage.