Industrial hemp (Cannabis sativa L.) is a widely used plant. It has been grown for a very long time, because it used to be an important source of fibres which were used for different purposes, from making clothes to sails. Nowadays its seeds are becoming more and more popular, mainly for their nutritional value, as they represent an important source of protein and essential fatty acids. They contain many beneficial macro- and micro-nutrients, alongside antioxidants, such as phenolic compounds. The oil of hemp seeds has been recognized as functional food. The results of different studies show that among phenolic compounds present in seeds or oil, flavonoids are the most abundant. They include a special group of so called cannflavins, which are unique to hemp. It has been found that beside flavonoids, some representatives of stilbenes and lignans are also present. All of these compounds aren't just good antioxidants, but have also shown some other beneficial effects.