A method for retransmitting a multicast frame in a wireless network and a method for determining whether or not a received multicast frame is a duplicated frame are disclosed. In determining whether or not the received multicast frame is the same duplicated frame as a previously received multicast frame, a receiver address value and a sequence number of the multicast frame may be used. When fragmentation of a multicast frame is allowed, the value of a fragment number of the multicast frame may be also used, and if it includes a traffic ID, the value of the traffic ID can be also used for determining whether or not the multicast frame is a duplicated frame. If a multicast frame is transmitted in a wireless mesh network, it is determined whether or not the multicast frame is a duplicated one by using a mesh source address, a mesh destination address, and a sequence number. The fragment number and/or the traffic ID may be also used in the determining step as necessary.