This paper proposes an efficient multiuser relay scheme in OFDMA systems. In the proposed scheme, multiple terminals transmit their data packets simultaneously in the same subband and multiple relay stations retransmit their received signals in different subbands after subband conversion. A base station (BS) extracts individual packets from received signals in the different subbands. In advance of data transmission, the BS selects appropriate terminals so that the BS can extract individual data packets successfully. Numerical results show that the proposed relay scheme achieves higher system throughput than the conventional relay scheme when scheduling is applied to a larger number of terminals than the number of relay stations.