The formation of benzoic, sorbic and nucleic acids during fermentation of milk with different commercial lactic acid bacteria starters was the object of this study. The changes of these organic acids content during storage of fermented milk were investigated as well. It was determined that benzoic acid content in fermented milk was 14–23 mg/kg, sorbic acid content was 0.06–0.085 mg/kg and nucleic acids content was 70 – 80 mg/100 mL. In comparison with raw milk the benzoic, sorbic and nucleic acids content in fermented milk was higher 5.1, 4.0 and 2.5 times, respectively. The most intensive formation of organic acids was detected during 3–6 h of milk fermentation, i.e. during the log phase. The organic acids content in fermented milk was affected by the type of commercial lactic acid bacteria starters while the highest concentration of the organic acids was detected in the milk fermented by starter La-5 containing Lactobacillus acidophilus bacteria. However, no influence of a starter type was noticed on the changes of organic acids during storage of fermented milk. In all cases the benzoic and sorbic acids content decreased during storage and no changes of the nucleic acids content were detected.