A method and apparatus for performing a wireless local area network (WLAN) termination (WT) addition/modification procedure in a wireless communication system is provided. For the WT addition procedure, an eNodeB (eNB) transmits a WT Addition Request message to a WT via a Xw interface, and receives a WT Addition Request Acknowledge message from the WT via the Xw interface. For eNB initiated WT modification procedure, the eNB transmits a WT Modification Request message to a WT via a Xw interface, and receives a WT Modification Request Acknowledge message from the WT via the Xw interface. For the WT initiated WT modification procedure, the eNB receives a WT Modification Required message from a WT via a Xw interface, and transmits a WT Modification Confirm message to the WT via the Xw interface. The WT is a logical node that terminates the Xw interface.