Cooperative Automatic Retransmission Request (C-ARQ) schemes allow those users which overhear a transmission to act as spontaneous relays when a packet has been received with errors at destination. When these users assist a source-destination pair in the retransmission process, the area exposed to the original transmission increases in comparison with non-cooperative ARQ schemes. In addition, the extension of the transmission time, due to the retransmissions, increases the vulnerability of a transmission to the hidden terminal problem. The paper provides a performance analysis of the hidden and exposed terminal effects in an 802.11-based wireless network where a C-ARQ scheme is executed at the Medium Access Control (MAC) layer. The presented analysis is supported by computer-based simulations.