A method and apparatus for preventing a plurality of stations in a wireless local area network (WLAN) from colliding with each other when accessing a medium are provided. In the method, an access point (AP) determines the transmission capabilities of a plurality of stations in a basic service set (BSS) of the AP, determines the format of control frames or data frames which have a high throughput (HT) format to be used in the BSS of the AP, and notifies the stations of the result of the determination. Therefore, it is possible to adaptively choose and use an optimum method of preventing a plurality of stations in a WLAN from colliding with each other when accessing a medium according to the circumstances in a WLAN by referencing the transmission capabilities of a plurality of stations in the WLAN.