Nowadays, tendency to improve human nutrition and consume new healthful foods such as low-calorie and functional ones has been increased. In this study, effects of ratios of sucrose/D-tagatose (100:0, 0:100, or 50:50) as well as type of commercial probiotic strains (Lactobacillus acidophilus LAFTI L10, Lactobacillus casei LAFTI L26, Lactobacillus rhamnosus HN001, and Bifidobacterium animalis subsp. lactis LAFTI B94) on biochemical and microbiological characteristics, percent of residual sugar, color, and sensory attributes of synbiotic chocolate milk were investigated during 21 days of refrigerated storage (5°C). The treatments inoculated with L. acidophilus, L. casei, L. rhamnosus, and B. lactis showed significantly higher biochemical and color changes compared to non-probiotic ones. The greatest viability at the end of storage was related to the treatment of D-tagatose