[en] In Turkey, sweet cherry production reached at 195,000 tons in the last two years. This value is 13% of the world production. Globally USA was the largest exporter of cherries in 2004, accounting for 21,2 % of world trade, just ahead of Turkey, which accounted for 20,07 %. The major high quality and exporting sweet cherry variety is 0900 Ziraat. It is a mid to late season variety with heart fruit shape, pink and very firm flesh and excellent flavor. Contrary to good traits, 0900 Ziraat is self incompatible, trees tends to grow vigorously with low yield on standard rootstocks. Although has some disadvantages there is huge demand from exterior market for 0900 Ziraat sweet cherry cultivar. In this research, gamma irradiation based mutation breeding technique was applied for improving of 0900 Ziraat. For this aim scions were irradiated 25, 30, 35, 40, 45, 50, 55, and 60Gy doses with Co⁶⁰ as a source of mutagen. After irradiation scions were budded on P.avium rootstock in greenhouse, located on Ministry of Agriculture, Yalova Atatierk Horticultural Central Research Institute. At the end of the first year young trees were transferred from greenhouse to orchard. According to 60 days data 'efficient mutation dose' was calculated. After the first year, which was including physiological effects, trees were characterized according to pomological traits such as fruit weight (g), peduncle length (cm), fruit width (cm), fruit height (cm), seed weight (g), soluble solid contents (%), yield (g), and cracking rate (%). Among the 371 living mutant trees in M₁V₇ generations, nominee of dwarf, large fruits (>30 mm) and high yield types were observed and data were observed. According to the data 58 mutant variety candidate were selected for advance observations. (author)