A total of 1050 samples of maize silage taken at various depths on premises for storing ensilaged feeds. The presence of eight species of microscopic fungi was demonstrated in the sampled silage: Mucor, Penicillium, Aspergillus, Alternaria, Trichoderma. It was established that highest was the number of species in the surface layer of the ensilaged mass. Considerably less were the species at a depth of 1.5 m, and then again the number of species rose toward the ground layer of silage. It is believed that lactic acid fermentation and the aerobic conditions exerted mycostatic effects. It was also demonstrated that with the aging of silage fungal species of the Fusarium and Trichoderma genera disappeared.