The Birmingham positron camera for tracking positron-emitting particles has been successfully applied in a wide range of fundamental research and industrial applications. The technique was developed to track a single tracer; however, tracking multiple particles would provide more comparative information on the physical processes taking place in a system. Here, multiple-particle tracking, a new method that is able to track more than one particle, is presented. The locations of each tracer are calculated in three dimensions by taking account of the radioactivity concentration of each tracer and by discarding corrupted γ-ray trajectories. The potential applications of the multiple-particle tracking technique are illustrated through two examples by tracking three stationary and three moving particles, respectively.