A slide rail includes an outer slide bracket, an outer slide, a middle slide, an inner slide, a plurality of first ball bearings, a first ball bearing bracket, a plurality of second ball bearings and a second ball bearing bracket. The outer slide is received in the outer slide bracket. The middle slide is received in the outer slide. The inner slide is received in the middle slide. The plurality of first ball bearings and the first ball bearing bracket are positioned between the outer slide and the middle slide. The first ball bearing bracket holds the first ball bearings. The plurality of second ball bearings and the second ball bearing bracket are positioned between the middle slide and the inner slide. The second ball bearing bracket holds the second ball bearings.