In this study, it was aimed to determine the effects of gibberillic acid (GA3) applications on drop and quality changes of fruits on-tree storage period. GA3 (before peel color break, on the peel color break and both periods) and 20 ppm GA3 (before peel color break and on the peel color break) were applied to the trees, and the untreated trees constituted the control group. Fruits were harvested in five periods at monthly intervals from april. In the last harvest period, the average fruit drop rate was significantly higher in the control group (38.48%) than in the color transformation 10 ppm GA3 (9.44%) and before color transformation 20 ppm GA3 (19.28%). The fruit drop was not observed in the first and second harvest periods. Especially in the first period on-tree storage, the shell C* and h° values of the fruits in control were found higher than the GA3 application. As a result, twice application of 10 ppm GA3 in 'Valencia Late' orange reduced pre-harvest fruit drop, delayed peel color transformation and limited fruit quality change. Accordingly, it has been revealed that it allows on-tree storability until the end of august.