In this study, the effects of different concentrations and forms of application of potassium sorbate on the microbiological quality of yogurt produced from cow's milk were examined during storage. Potassium sorbate was applied at concentrations of 50, 100, 200 and 400 ppm by addition to milk or by spraying onto the surface of yogurt. According to the results of the analyses, after 1, 7, 15 and 30 days of storage it was found that the different types of treatment with potassium sorbate had no significant effect on the microbiological properties of yogurt (p > 0.05). Whereas it was determined that the concentration of potassium sorbate had a significant effect on the counts of total aerobic mesophilic bacteria, aerobic spore-forming bacteria, psychrotrophic bacteria, yeasts and moulds (p 0.05). The storage period had a significant influence on total aerobic mesophilic bacteria, aerobic spore-forming bacteria, psychrotrophic bacteria and lactic acid bacteria counts (p 0.05)