The present invention relates to sunflower seeds which have been genetically modified through two artificial induction cycles of mutations followed in each case by processes for the identification of mutant individuals which have the desired character. The disclosed seeds are characterised in that they contain between 26% and 80% of the tocopherols as delta-tocopherol. This high delta-tocopherol production is determined by the genotype of the seeds which have been modified to this effect, and is always obtained independently of the culture conditions, thereby obtaining an inheritable character. Today, sunflower seeds producing such high levels of delta-tocopherol do not exist. Genetically modified sunflower plants which produce through self-fertilization seeds with high delta-tocopherol levels and the oil with high natural delta-tocopherol concentration, extracted from the seeds, are also objectives of the present invention.