SUMMARYMobile ad hoc networks attract tremendous attention as one form of future network configuration. Among wireless LAN technologies, the IEEE 802.11MAC standard can be considered as the most prominent technology deployed in ad hoc networks. For realization of mobile ad hoc networks, providing QoS support in ad hoc networks is an important task. Among numerous parameters of QoS, perflow fairness is an important and problematic issue in ad hoc networks. In the traditional wireline networks, per-flow unfairness occurs mainly due to the link layer. However, in mobile ad hoc networks, in addition to the link layer, the MAC layer has significant impact on per-flow fairness problems. In particular, although IEEE 802.11MAC provides per-node fair bandwidth allocation, in order to achieve per-flow fairness, a method that provides per-flow fair bandwidth allocation is required. In this paper, a new scheme is proposed that enables a fair bandwidth allocation to each flow. In addition to fairness, the proposed scheme provides a positive impact on the network in terms of total performance and medium utility. The performance of the proposed scheme is investigated with an ns-2 network simulator.