A ball bearing slide assembly includes a first slide, a second slide, a slide-aiding member, and a positioning member. The first slide is slidably received in the second slide. The slide-aiding member is slidably received between the first and second slides, and comprises a plurality of ball bearings slidably sandwiched between the first and second slides. The slide-aiding member defines a locking hole. The positioning member is mounted to the second slide and forms a resilient cantilever. A positioning block is formed on the resilient cantilever and engages in the locking hole of the slide-aiding member for temporarily locking the slide-aiding member to the second slide, such that the first slide is slidable inward without pushing the slide-aiding member inward. The first slide deforms the cantilever to disengage the positioning block from the locking hole, such that the slide-aiding member is slidable relative to the first and second slides.