A slide rail assembly includes a first rail, a second rail, a third rail, a synchronization member and a fastening member. The third rail is movably mounted between the first and second rails. The synchronization member and the fastening member are movably mounted to the third rail. The synchronization member is configured to engage with the second rail, such that the second and third rails can be synchronously moved relative to the first rail along an opening direction. When the second and third rails are moved to a first predetermined position, the synchronization member is disengaged from the second rail. When the third rail is moved from the first predetermined position to a second predetermined position along the opening direction, the third rail is fastened to the first rail by the fastening member to prevent the third rail from being moved relative to the first rail along a retracted direction.