The viability of 5 probiotic lactobacilli strains (Lactobacillus acidophilus LA-5, Lactobacillus casei L01, Lactobacillus casei LAFTI L26, Lactobacillus paracasei Lcp37, and Lactobacillus rhamnosus HN001) was assessed in 2 types of probiotic flavored drink based on fermented milk during 21 days of refrigerated storage ($5^{circ}C$). Also, changes in biochemical parameters (pH, titrable acidity, and redox potential) during fermentation as well as the sensory attributes of final product were determined. Among the probiotic strains, L. casei LAFTI L26 exhibited the highest retention of viability during refrigerated storage period, while L. acidophilus LA-5 showed the highest loss of viability during this period. The decline in cell count of probiotic bacteria in strawberry fermented milk was significantly greater compared to peach fermented milk. In an overall approach, peach fermented milk containing L. casei LAFTI L26 was selected as the optimal treatment in this study in both aspects of viability and sensory accpeptibility.