Currently, natural antioxidants and substances with a protective effect on fatty acids are used more and more often instead of synthetic compounds that may have a negative impact on human health. This is related to the prevailing trend of promoting healthy and organic food. Essential oils are interesting in this respect because studies confirm their antioxidant properties. The aim of this study was to analyse the effect of the addition of marjoram oil on the inhibition of changes in the fatty acid profile of rapeseed oil, stored under different temperature conditions. In the experiment, marjoram oil and BHA were added to the batches of rapeseed oil. The samples of rapeseed oil with the addition of marjoram oil and BHA were stored at room temperature and at 40 °C. The negative effect of storage on quantitative changes in fatty acid profile of rapeseed oil was observed. It was found that the ability of selected substances to inhibit unfavourable transformations in fats depends on their concentration and the temperature of storage. Marjoram oil can potentially be used as an additive stabilizing the fatty acid profile in vegetable oils.