The influence of chilling on flower bud burst and flowering of sweet cherry cv.‘0900 Ziraat’and the chilling requirements were studied. Flower buds of Lambert, Windsor, Kırdar and 0900 Ziraat varieties from trees in different time, with different chilling, were collected to compare their activation and flowering. Each hour daily temperatures were recorded and total-chilling requirements was calculated below 7.2 ºC from the beginning of November to the end of March. Flower buds from the insufficient chilling were found to be more delayed their activation. One of the most noticeable effects of the low chill was the delayed flowering in flower bud of Lambert, Windsor and 0900 Ziraat varieties. The chilling requirement of sweet cherry cv.‘0900 Ziraat’was above 1555 hours.