In this paper, a cooperation protocol for MC-CDMA systems is proposed and validated by means of computer simulations. The use of different equalization techniques is compared in several transmission scenarios. Network configurations with more information sources and relays are considered too. The effects of a weak reliability of the radio link between source and relay are pointed out. It is included the multiple access interference that emerges in the up-link of MCCDMA systems. The effectiveness of the cooperation process is shown to be tightly related to the capability of the relay devise to correctly estimate the information data generated by the source. The proposed cooperation strategy can bring to a remarkable performance improvement in terms of exploitable diversity and power gain at the expense of a data throughput loss and complexity increase.