—In this paper, we investigate diversity gain in coding for a 2-user multiple-access-channel (MAC) with cooperating transmitters–the MAC with relaying. We propose a simple distributed space-time-frequency block coding (D-STFBC) scheme and analyze the offered diversity gain. In particular, we show that full diversity (order 3) is possible if collaboration is well enough and rigorous signal processing is assumed both at the transmitters and the receiver. Bit-error-rate (BER) analysis and curves are provided for illustrative purposes.