A method and apparatus for performing a random access procedure in a wireless communication system is provided. A user equipment (UE) performs a contention free random access procedure on a first frequency, detects a failure of the contention free random access procedure, and performs a contention based random access procedure. When the first frequency is occupied by other media as a result of listen-before-talk (LBT) operation, the contention based random access procedure may be performed on a second frequency.