Immature zygotic embryos from the Spanish self-pollinated sunflower line Z-8-A (Helianthus annus L.) were used as donor material to induce direct organogenesis. A portion of the isolated immature embryos were treated with gamma radiation (137Cs) at a dose of 5 Gy before plating. The range of the spontaneously induced somaclonal variation among the obtained regenerants was investigated and compared with that of the variants induced through irra diation. The genetic changes occurring during the regeneration procedure included sixteen morphological and biochemical characters. The most significant changes were observed for the following characters: plant height, number of leaves, stem diameter, head diameter, length of branches, oil content in seed (%) and 1000-seed weight. The study showed that the somaclonal- (R9) and the radiation-induced (M9R9) variants revealed similar spectra of morphological and biochemical changes, thought with different frequency.