The present study was carried out during two successive seasons (2004 and 2005) to evaluate different cultivars of Peach namely "Florda Prince", "Florda Gold" and "Early Grand" under different environmental conditions in two locations in El-Wahat El-Baharaia and El-Badrashin Giza, Egypt. The trees under study were 12 years old, budded on Nemagard Rootstock; The planting distances were (5 X 5m). The evaluation included the Growing Degree Days needed for bud burst, flowering, fruit set, harvesting using base temperature (4.4⁰C) and comparison between all cultivars in the two locations. Data indicated that "Florda Gold" cultivar required higher G.D.D. for bud burst, flowering, fruit-setting and harvesting than that observed in both "Florda Prince" and "Early Grand" cultivars. Whereas "Early Grand" cultivar need, the lowest G.D.D.. Both Bud burst and Flowering need more G.D.D. in the first location than the second one. However in "Florda Prince" and "Florda Gold" cultivars the G.D.D. need for Fruit set was more in the first location than the second one. On the other hand, in all cultivars harvesting need more G.D.D. in the second location than the first one.