The aim of this study was to observe the dynamics of nitrates and nitrites during the six stages of manufacture of Emmental cheeses. Samples were taken of untreated milk, of pasteurized milk, of milk with nitrates added, of pressed cheese curd, of whey, of maturing cheese and of the final product. The samples were drawn from a commercial operation in a cheese factory in the eastern part of Slovakia. The mean NaNO2content in untreated and in pasteurised milk was 0.2 and 0.1 mg kg-1, respectively and the mean NaNO3content was 0.9 and 0.9 mg kg-1respectively. Nitrates were added to the milk to prevent ‘blowing’ of hard cheese by micro organisms. In milk with nitrate added the mean content was 81.2 mg kg-1NaNO3; the maximum value being 90.0 mg kg1NaNO3. After pressing, the mean value of nitrate was found to be 20.6 mg kg-1NaNO3. A considerable quantity of nitrates passed into the whey, where the mean nitrate content was 67.0 mg kg-1NaNO3. The final product had a markedly decreased content of nitrates (3.3 mg kg-1NaNO3) and nitrites (0.2 mg kg-1NaNO2) when compared with the values in cheese during maturation (11.3 mg kg-1NaNO3; 0.4 mg kg-1NaNO2).