Plant growth regulators play a vital role in flower bud formation and development of floral parts. To this effect, 22S, 23S-homobrassinolide (HBr) and GA(3) were tested on 'Bing' sweet cherry to determine their influence on the occurrence of doubling during the development of buds, flowers and fruits. The substances were applied for a 2-year period with a handgun sprayer at the transition stage from sepal to petal differentiation. GA(3) was applied at 25, 50, and 100 mg L-1, and HBr at 0.05, 0.1 and 0.5 mg L-1. The results showed that the percentage of doubling (buds, flowers and fruits) was increased with all applications of HBr. GA(3) decreased double ovaries during full bloom and the percentage of double fruits in the following year. In all experiments (except for 25 mg L-1 GA(3)) the frequency of double pistils in the flowers at full bloom was lower than that observed in the buds the previous autumn. The frequency of double fruits in the first year of treatment was lower than in the second year of treatment.