In this study, the physicochemical properties (pH, acidity, dry matter, ash, protein, fat, syneresis, viscosity), sensory properties and viability of Lactobacillus plantarum of yogurt samples prepared from cow's milk (100%) and vegetarian yogurt samples prepared from soy-hazelnut milk in different ratios (0:100, 5:95, 10:90 and 15:85) were evaluated in a completely randomized design with three replications and during 20 days of storage. The ash (1/6%), dry matter (15/8%), fat (3/5%) and protein (3/6%) content of cow's milk yogurt samples were significantly higher than those of soy milk yogurt samples (1/14%, 13/04%, 2% and 3/15%, respectively), and in plant-based yogurt samples, all the factors studied except fat decreased with increasing hazelnut milk content (p<0/05). The viscosity of cow's milk yogurt samples (2532 mPas) was higher compared to plant-based yogurts (554 mPas). Also, in plant-based yogurt, the syneresis of soy milk yogurt samples (11/41) was lower than that of yogurt samples prepared from soy milk-hazelnut milk mixture (1/54). The survival of Lactobacillus plantarum bacteria in cow's yogurt samples (8/65 cfu/g) was higher than that of yogurt samples prepared from plant-based milks (7/69 cfu/g), and in plant-based yogurt samples, the survival of Lactobacillus plantarum bacteria improved with increasing percentage of hazelnut milk (8/39 cfu/g) (p<0/05). According to the sensory evaluation results, in all factors studied, yogurt samples prepared from cow's milk had a higher score compared to plant-based yogurt samples. Also, according to the evaluators, treatments T1 (100% soy milk) and T2 (95% soy milk and 5% hazelnut milk) were the most acceptable among the plant-based yogurt treatment samples. Finally, yogurt samples prepared from cow's milk had better nutritional, textural, microbial and sensory quality compared to plant-based alternatives. However, for vegetarians, yogurt production from soy milk or soy milk-hazelnut milk blends, especially samples with a lower proportion of hazelnut milk, could be considered.