Multi-carrier code division multiplexing (MC-CDM) is one of promising multiplexing techniques for fourth-generation mobile downlink communications systems, where high data rate services should be provided even for high speed-cruising mobiles. This paper proposes an MMSE (minimum mean square error)-based adaptive equalizer for MC-CDM downlink system which utilizes the pilot signals effectively. Furthermore, the performance of the proposed system in a frequency selective fading channel is compared with that of a conventional system by computer simulation.