The research objective was to determine the ozone effect on molds colonizing wheat grains. The ozone used in the experiment was produced by an ozone generator. The wheat grain exposure time to ozone was 0.5, 1, 3, 6 and 9 h, respectively. The studies showed ozone to effec-tively control molds colonizing wheat grains. The studies established the exposure time resulting in the lowest reduction rate of microorganisms as well as ozonation treatment time required to attain the highest level of grain disinfection be safely administered to animals.