A slide rail assembly includes a first rail, a second rail, a third rail, a locking member and an operating member. The second rail is movable relative to the first rail between a first position and a second position. The third rail is movable relative to the second rail. The locking member is mounted to the second rail. When the second rail is located at the second position, the locking member is configured to lock a portion of the first rail, such that the second rail is not movable relative to the first rail from the second position toward the first position. The operating member is configured to be operated by a user to unlock the portion of the first rail from the locking member.