Wireless communication has been rapidly developed in recent years acquiring higher demand of efficient wireless systems. Cooperative communication is considered to be capable of effectively meeting this rapid growth where the use of relays improves the throughput and ensures successful transmission to all terminals in a given system. In this paper, a Two-way Decode and Forward Relaying for orthogonal frequency division multiple access (OFDMA) mobile systems (TWR-DF-oFdMA) is proposed. The system consists of mobile terminals (MTs) divided into near nodes and far nodes in which the base station directly transmits to the near nodes and indirectly transmits to the far nodes by the cooperation of the near nodes which act as relays. The performance of the system is measured in terms of the bit error rate and the sum rate. It is found that the performance of TWR-DF-OFDMA is much better than that of conventional OFDMA. Furthermore, it is shown that the number of NNs in the system affects the performance of TWR-DF-OFDMA and an optimum number was found to give the highest performance of TWR-DF-OFDMA compared to conventional OFDMA.