The influence of hydrogen cyanamide (HC) on the flower bud development of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson). 'Hayward' was studied. The bud samples were taken every 5-10 d starting from dormant season (March) and fixed in FAA (10% formalin, 50% ethanol, 5% glacial acetic acid). Flower bud development was compared in three HC concentrations and the control. 1%, 2%, and 3% of HC was applied 35 d before the expected natural bud break. During the onset of bud break, only 57.6% of control buds had sepal primordia developed. On the other hand, HC treated buds had almost completed their stamen formation and started stigma primordia. When the control vines were in advanced bud break, gynoecial plateau already began to form in the vines treated with 2 and 3% HC. Vines treated with 1% HC lagged a little behind and had not started developing the gynoecial plateau. As the bud developed from the open cluster to the tight bud stage, the differences between the control and HC treated plants were more distinct. However, there were no differences between HC treatments as the ovule initiation took place in the buds.