Abstract: The effect of gibberellin on abscission of petiole of Euonymus japonica stem segment and cotton seedling segment was studied. The results showed that application of GA3 caused a marked increase in abscission of petioles. The effect was prominent in a definite range with the increase of the concentration. GA3 had no direct effect in stimulating ethylene production but it induced an increase of respiration. Abscission of petioles was decreased by the addition of glucose into the culture medium. The difference of GA3 effect in both intact plant and explant has been discussed.