Abstract: The effect of gamma irradiation and gibberellic acid (GA3) treatment on different responses of fennel was investigated. Combined effect of -irradiation at 2 Krad dose and GA3 treatment at 50 mgL -1 concentration resulted in the maximum germination percentage, seed production, essential oil yield, as well as the best quality of fennel (Foeniculum vulgare) oil because of its high content of the flavour compounds, e.g. trans-anethole and fenchone. GA3 application reduced the harmful effects of higher irradiation doses (5-20 krad).