Regarding the influence of nitrate in fermentation process of ensiling green forage, the question arises whether and in which extent the nitrate of green forage reduced to ammonia in the fermentation phase of pH-reduction and whether the nitrate has an influence on contents of acetic acid. The fermentation process under laboratory conditions was proved in 5 variably contents of dry matter (DM) in green forage (20 .. 60%) and with respective higher addition of nitrate (0; 2,2; 4,4; 6,7g NO3/kg DM). It was demonstrated that the nitrate in fermentation phase of pH-reduction has not an influence of contents of acetic acid, ammonia and alcohol in silages. The process of heterofermentic lactic acid fermentation cannot be influenced by nitrate. It was also demonstrated that nitrate has not been reduced to ammonia in anaerob stable silages, apart from formation of nitrose gases (in green forage with nitrate always to start of fermentation process). Conclusions to material changes in the fermentation process, with and without nitrate in green forage, were driven.