Yogurt has an important role in our nutrition but also has a therapeutic role in the protection and development of health (6). Yogurt is briefly defined as a clot formed by fermentation and precipitation of milk proteins (7). Yogurt is traditionally produced by fermentation of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus starter culture (8). Most of the classic ABSTRACT Objective: This study was performed with the aim of determining the effects of different levels of cinnamon which were added to probiotic yogurts on the microbiological, chemical and sensory properties of these yogurts. Methods: In this study, probiotic yogurt was produced using yogurt and probiotic yogurt cultures. Yogurts are divided into four groups; control, cinnamon 1, cinnamon 2 and cinnamon 3 groups. To the groups, 0%, 0.3%, 1% and 2.5% of powdered cinnamon were added, respectively. Content analysis of cinnamon used in the study was conducted by gas chromatography-mass spectrometry method. Results: The addition of cinnamon to probiotic yogurt showed antibacterial activity on Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium animalis ssp. lactis while cinnamon depending on its concentration was found to support bacterial growth of Lactobacillus delbrueckii subsp. bulgaricus. The pH values and the fat-free dry matter ratios varied depending on the proportion of cinnamon added to the yogurts. When the sensory characteristics of yogurt were compared, the score of the control group was higher than the score of cinnamon groups. On the other hand, cinnamon (1%) group had the closest score to the sensory analysis score of the control group. Conclusion: These results have shown that cinnamon added at different ratios in probiotic yogurt has a limited positive effect on the microbial, chemical and sensory properties of this food.