As far as the proportion of saturated and unsaturated fatty acids is concerned, the composition of the fatty acids contained in soybean oil is most favourable. It is one of the most important natural sources of essential fatty acids, containing not only n-6, but also n-3 fatty acids, too. Soybean oil is starting material for margarine production. A large number of leguminous plants, soybean included, contain phyto-estrogens, isoflavons, of similar structure and effects with human oestrogen hormones, less active, but present in higher concentrations. Therefore soybean oil plays a protective role in menopause, osteoporosis, heart, artery and tumour diseases.