This paper proposes a multi-channel medium access control (MAC) protocol for wireless mesh networks (WMNs) by using busy tones to prevent data packet collisions at data channels. Multi-channel MAC schemes can achieve higher network throughput than single channel MAC schemes in multihop wireless networks. It is especially appealing to exploit multiple channels in WMNs which has high capacity requirement to support backbone multimedia applications. Most previously proposed MAC protocols make use of the RTS/CTS mechanism to deal with data packet collisions caused by exposed/hidden terminal problems in multihop environment. However, when multiple channels are used for data transmissions, the RTS/CTS mechanism can no longer handle the exposed/hidden terminal successfully. By investigating the special features of WMN architecture, we apply the busy tone solution into the medium access control mechanism for WMNs, in which mesh nodes have no limit on power consumption. In this paper, we clearly presented the idea and operation of our proposed multi-channel MAC protocol for WMNs. Comprehensive simulation is underway to compare the performance of our proposed mechanism with that of other RTS/CTS-based multi-channel MAC protocols.