Fruits of ‘Xile’ and ‘Venus Seedless’ grapevines were treated with GA₃ at 0, 10, 25, 50, 100 or 200 mg·L^-1 after full bloom. The results showed that GA₃ treatment increased fruit size and hardness and delayed fruit ripening. The effect of GA₃ on fruit quality varied in different varieties. In ‘Xile’ grape, low concentrations GA₃ (10, 25 and 50 mg·L^-1) significantly increased the total soluble solid (TSS), TSS to titratable acid content (TAC) ratio, and soluble sugar content (SSC), but decreased TAC. Treatment of 50 mg·L^-1 GA₃ showed the most significant effect; however, in ‘Venus Seedless’, fruit quality was lower in all GA₃ treatments than in water control.