The research material constituted fruit of two genotypes of A. arguta (L1, M1) and of three hybrid genotypes of A. arguta × A. purpurea (D8, D11, D14). The material for comparison was an ‘Ananasnaja’ (=’Anna’) cultivar known as the most commonly cultivated hardy kiwifruit throughout the world. All the plants were obtained under a special plant growing programme at the SGGW University in Warsaw, and the fruit came from plants grown at the SGGW experimental field station in Ursynów in Warsaw. The research was carried out during 2005 and 2006. The contents of vitamin C and polyphenols were determined in the fruit of the genotypes under research, as was the antioxidant activity. The results obtained confirmed the fruit of A. arguta to be a rich source of vitamin C, however, its content depended on individual features of the genotype. It was found that the content of vitamin C was higher in the fruit of hybrid genotypes of A. arguta × A. purpurea if compared with the genotypes of A. arguta. The hybrid genotypes of D11 and D14 showed a significantly higher antioxidant activity that was correlated with the content of vitamin C. They were also characterized by a higher content of phenolic compounds than the fruit of other Actinidia species studied.