The drying on a drum dryer is one of the energy-efficient methods of dehydration. Instant cereal based flakes are produced with this procedure. The flakes of corn and rice with added vitamins contain polyunsaturated fatty acids and have low water activity and in the presence of oxygen can create a reaction of lipid oxidation. By packaging the products in a modified atmosphere, the atmosphere inside the packaging is changed by the displacement of oxygen with nitrogen, in order to improve the shelf life. The aim of this study was to determine whether a modified atmosphere packaging can preserve the chemical and sensory properties of corn and rice flakes with added vitamins. Flakes were packaged in both a modified atmosphere and common atmosphere and stored at room temperature and in a thermostat on 37 °C. During five months of storage changes in chemical composition, like the amount of fat, fatty acid composition, fat acidity, amount of total sugar and starch were monitored. In addition a sensory properties of products were monitored by the method of quantitative descriptive analysis. Undesirable changes in sensory properties such as rancid taste and odor appeared in the products packaged in a common atmosphere and stored at room temperature after four months of storage and the reduction in the amount of polyunsaturated fatty acids appeared after the third month. When the products were packaged in a common atmosphere and stored in thermostat, these changes were of greater intensity than in products packaged in a common atmosphere and stored at room temperature. Products packaged in a modified atmosphere did not differ significantly in chemical and sensory properties of the products after manufacturing. During the observed five months, the share of polyunsaturated fatty acids in the fat of products packed in a modified atmosphere and stored in a thermostat at the temperature of 37 °C did not change and there was no significant change in the sensory properties of corn and rice flakes with added vitamins. The obtained results indicate the justification for using the modified atmosphere as packaging technology.