In order to study the effects of priming on seed germination and seedling growth of Cucurbita pepo under copper stress conditions, an experiment was conducted. Seeds of cucumber were soaked in aerated solution of GA3, 2 mM (hormonal priming) and in distilled water (hydro-priming). The results showed a trend of tolerance to the effects of copper at different concentrations on seed germination of Cucurbita pepo. The hydro-priming improved the morphology of germinated seeds in Cucurbita pepo. Similarly, it enhanced the tolerance index and the T/50 in the no stressed seeds by copper. Priming with GA3 at low dose had no effect on seed germination of this species.