This is an aeropalynologic study carried out by the use of gravimetric method in the central region of Bursa between March 1991 and March 1992. For this purpose a Durham pollen collection apparatus was placed to the roof of a high building stuating at the city center of Bursa. It was found that 70% of total pollen amounts were belong to the tree taxa and 27% to the herbaceous taxa. Tree pollens in Bursa atmosphere reached to the maximum in April, May and June. Pollen amounts have showed and increase till June together with the raise of temparature. A decrease was determined in total pollen amounts in summer according to spring, and also herbaceous pollens determined much more than tree pollens in this period. It was seen that heat and drought were played an important role in the pollination period finished of most plants, very few amounts pollens were found in September, October and November. No pollen was seen in December and January.