The genus Actinidia has been recorded as having total six taxa, composed of four species and two varieties, in Korea. However, its taxonomy remains complex because of disagreement on taxonomic characters used for species boundaries. Based upon morphological, anatomical, and palynological characters, we re-evaluated species delimitations in the genus Actinidia. Critical observation of wild populations and extensive herbarium materials including types were also carried out. It is generally considered that leaf thickness and shape, hair type and color were important diagnostic characters to identify species, but these characters were insufficient to be diagnostic characters because of their wide variation ranges. On the other hands, pith pattern, winter bud protrusion rate, scale leaf number, anther color, fruit shape, and maturity season were taxonomic significance. A. arguta var. platyphylla and A. arguta var. rufinervis have been identified by hair type and color, but these characters showed continuous variation in A. arguta. Therefore, two varieties are treated as synonyms of A. arguta. Consequently four species are recognized in Korea: A. polygama, A. kolomikta, A. rufa, and A. arguta. A key is provided, as well as complete descriptions of the species examined, including information on nomenclatural types, and synonymies.