In this Letter, the authors consider a multi-unicast flow wireless communication system with a retransmission scheme. The effective capacity (EC) is used as a performance metric in order to make use of the recurrence relation approach. They also take advantage of network coding (NC) as combined with automatic repeat request (ARQ) protocol (NC-ARQ), for more robust communication. The authors' main contribution, in this work, is the derivation of the EC for M-user NC-ARQ using only the opportunity of XoR-ing M packets. They then, focus on a 3-user system and derive the EC using the opportunity of XoR-ing packets for 3 and 2 users. An interesting result is the fact that, contrary to expectation, as the number of users in a network that uses NC-ARQ increases, the performance in terms of EC increases as well, depending on how the sender schedules and manages the retransmissions.