Desirability and good background of yogurt have led the manufacturers to use this product mostly for producing milk-based probiotic products. The aim of this study was to evalutate the effect of a mixture of prebiotics including oligofructose, lactulose, and inulin on physicochemical properties (pH value, acidity, and syneresis) of synbiotic yogurt containing lactobacillus casei. Pasteurized milk was inoculated with certain amount of starter, prebiotic, and probiotic bacteria, then yogurt samples were prepared, and at 1, 7, 14 and 21 d, pH value, acidity, and syneresis were measured by pHmeter, titration method, and centrifuge, respectively at certain intervals. The results showed that the sample containing the mixture of lactulose, inulin and oligofructose (LIO) had the lowest pH value, highest acidity and syneresis. In contrast, the sample containing lactulose and inulin mixture (LI) had the lowest acidity and syneresis showing a significant difference from the control (probiotic yogurt without prebiotic). The variation trend of acidity and syneresis was rising and the sample containing lactulose and inulin (LI) mixture contained sample was selected as the best synbiotic yogurt sample. Manuscript profile