The present invention relates to methods and arrangements in a radio base station and in a user equipment for controlling the downlink transmit power of the F-DPCH in a multi-carrier HSPA system, by using the concept of TPC commands (used in single-carrier systems), adapted to support different kinds of multi-carrier scenarios. The UE defines at least one TPC command for adjustment of the transmit power of the N downlink carriers' (203) F-DPCH, the number of TPC commands being equal to or lower than N, and transmits the TPC command(s) on at least one of the M uplink carriers (201, 202). The radio base station receives the TPC command(s) on the M uplink carriers from the user equipment, and adjusts the transmit power of the N downlink carriers' F-DPCH based on 10 the received TPC command(s).