42 samples of yogurt and kefir coming from different commercial centres were investigated. Average nitrate content in yogurt is 3,7 mg NO3/dm3 while in kefir 2,7 mg NO3/dm3. The level of nitrate ions in both bevegerages is comparable with amount of nitrate ions in quark or curdled milk. Research has shown that nitrite did not occur in any samples of yogurt and kefir. Yogurts stabilized by gellatin or modified starch content more nitrate ions than yogurts stabilized by pectin. Acidity of kefir samples has influence on nitrate levels.