An attempt has been made in the present study to explore the potential of Spirulina, a cyanobacterium, photoautotrophic microorganism in initiating a stimulatory effect on the microflora of Probiotic yoghurt. Probiotic yoghurt was prepared by adding 1 percent inoculum of probiotic Bifidobacterium bifidum to yoghurt cultures viz., Streptococcus. salivarius ssp. thermophilus and Lactobacillus. delbrueckii ssp. bulgaricus. Spirulina enriched functional Probiotic yoghurt was prepared by using 1 gram of Spirulina per litre of mix.The pH and acidity of probiotic yoghurt and Spirulina enriched Probiotic yoghurt on 0 day was 4.31± 0.007, 0.96± 0.002 and 4.31± 0.009, 0.96± 0.005 respectively. On the 3rd it was 4.30 ± 0.003, 0.96 ± 0.004 and 4.31 ± 0.004, 0.96± 0.005 respectively. There was no significant difference in the pH and acidity of Probiotic and Spirulina enriched yoghurt between these 2 sampling periods. The pH and acidity of probiotic yoghurt and spirulina enriched probiotic yoghurt on the 7th day was 4.28 ± 0.001, 1.11 ± 0.030 and 4.31 ± 0.004, 1.02 ± 0.023 respectively. Significant difference was noticed in pH and acidity in these two treatments on 7th day. The Spirulina enriched sample was less acidic than Probiotic yoghurt. There was virtually no difference in viable numbers of S. salivarius ssp. thermophilus, L. delbrueckii ssp. bulgaricus and Bifidobacterium bifidum on 0 and 3rd day. However the growth of the three lactic acid bacteria used was higher in Spirulina enriched yoghurt than in Probiotic yoghurt on the 7th day. The addition of cyanobacterial bio mass to Bifidobacterium bifidum, S. salivarius ssp. thermophilus and L. delbrueckii ssp. bulgaricus had beneficial effect on their viability. No spoilage organism was detected at any sampling time, indicating the high degree of sanitation during processing and packaging products. Thus the abundance of bioactive substances in Spirulina is of great importance from a nutritional point of view as it provides new opportunity for the manufacture of functional dairy foods.