Ion cyclotron resonance heating by radio-frequency (RF) waves, which are excited by a helically wound antenna, is observed for the first time in a fast-flowing plasma in the HITOP device. Dispersion relations of propagating waves are obtained experimentally and compared with theoretical ones. Stored energy W-perpendicular to and ion temperature clearly increase during the RF pulse. Heating efficiency is compared for various magnetic field configurations and strengths without any clear indication of the cyclotron resonance. This suggests that ion-ion collisional effect is dominant in the high-density plasma. When a ratio of ion cyclotron frequency to ion-ion collision one becomes high, features of ion cyclotron resonance are clearly observed. (c) 2005 Elsevier B.V. All rights reserved.