Objective of this study was to examine the effects of global warming on pollen germination in fruit trees. For this purpose Bigarreu Gaucher, Celeste, Lambert, Lapins, Starks Gold, Stella and 0900 Ziraat cherry cultivar's pollens were used. Pollen germination and tube growth rates were observed at 40%, 50%, 60%, 70%, 80% and 90% relative humidity regimes. High humidity regimes were gave best results for both pollen germination and pollen tube growth. 80% was the optimum RH for in vitro germination of Starks Gold and Stella while 90% was optimum for Bigarreu Gaucher. In vitro pollen germination increased with increasing incubation relative and incubation period. 24 hours later was the optimum for all cultivars. The longest pollen tube length was obtained from 90% RH. Set fruitful could be affected by relative humidity and indirectly global warming.