Radix Actinidia chinensis Planch is a traditional Chinese herb, and its decotion had been widely used clinically to treat several types of cancer. In our study, the phenolic compounds constituting the major water soluble components of Radix A. chinensis were profiled and characterized by ultraperformance liquid chromatography electrospray ionization tandem mass spectrometry. A total of 50 compounds were identified or tentatively characterized, including caffeic acid, p-coumaric acid, 29 catechin derivatives, 12 quinic acid derivatives and 7 coumarin derivatives. Most of the identified compounds were firstly reported from A. chinensis. Among them, scopoletin, scoplin, isofraxoside and quinic acid derivatives have not ever been reported from genus Actinidia previously. These phenolic compounds might be responsible for the antitumor activity of the water extract of radix A. chinensis, and the established analytical method could be applied to further study of quality evaluation and active components of Radix A. chinensis. (C) 2014 Elsevier B.V. All rights reserved.