Efforts have been made to clarify the transition from the hermaphroditic to the unisexual condition in staminate and pistillate flowers of Actinidia deliciosa. Besides molecular markers, structural and biochemical markers for sexual determination have been sought through cyto-histological and biochemical investigations. The anatomical approach has considered the structural changes occurring in the developing ovaries both in male and female flowers, as well as the sequence of pollen developmental stages in the anthers. The biochemical investigation has been focused on the definition of the role of various substances in addressing macro and microsporogenesis. Recently polyamine metabolism has been proved to be related to sexual expression in kiwifruit. The current status of knowledge in these fields is reviewed in this paper and trends of future research are outlined.