The present study was carried out during two successive of 2016 and 2017 on 10 years old Balady mandarin (Citrus reticulate Blanco) trees budded on sour orange rootstock (Citrus aurantium L. Osbeck) and spaced 3.5×3.5 meters apart. Trees have been treated with girdling and gibberellic acid and were grown in sandy soil under drip irrigation system in a private orchard at Al-kamal region- Ismalia Governorate, Egypt, in July and December. The aim of this work was to study the effect of girdling and gibberellic acid on the vegetative growth, yield and fruit quality. The chosen trees girdled with 2 mm, 4 mm width and gibberellic acid was sprayed (at 50 and 100 ppm) alone or in combination with girdling in each season. Results showed that, girdling 4 mm+100 ppm gibberellic acid have given the best enhanced vegetative growth parameters in terms of leaf area, carbohydrate and chlorophyll contents in the leaves of Balady mandarin trees in both seasons. Moreover, treatment of girdling 4 mm in December and girdling 4 mm+50 ppm GA₃gave the best fruit length, diameter as compared to control treatment. Yield and fruit quality of the chosen trees were significantly increased by all treatments as compared to control in both seasons.