Contamination by microscopic fungi and mycotoxins in high moisture corn (HMC) silages conserved by chemical additives was investigated. The samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and for mycotoxins content (deoxynivalenol, T-2 toxin, zearalenone and total aflatoxins, fumonisins, ochratoxins) by direct competitive enzyme-linked immunosorbent assays. The average fungal counts were 3.37 ± 2.52 log cfu/g in control HMC silages, 2.91 ± 0.51 log cfu/g in HMC silages treated by organic salts and inorganic salt, 3.62 ± 1.46 log cfu/g in HMC ensiled with organic acids and 3.49 ± 1.12 log cfu/g of HMC silages treated by organic acids along with organic salt. In this study, 740 isolates belonging to 10 fungal species representing 9 genera were recovered. The genera of microscopic fungi most frequently found in HMC were Penicillium (56.49 percentages) and Paecilomyces (32.16 percentages). T-2 toxin was the secondary metabolite with the highest concentration ranging from 179.13 ± 3.04 to 249.40 ± 24.69 micrograms/kg, followed by deoxynivalenol and total fumonisins. The highest mean of deoxynivalenol level was 0.13 ± 0.02 mg/kg and concentration of total fumonisins ranged from 20.13 ± 2.53 to 90.33 ± 10.35 micrograms/kg. This study indicated that application of chemical additives containing organic acids, organic salts and inorganic salt was sufficient to inhibit mycotoxins formation. The use of calcium formiate, sodium benzoate and sodium nitrite resulted in high hygienic quality of HMC silages and significantly reduced the concentration of zearalenone, deoxynivalenol and total ochratoxins and fumonisins.