A mixed H-2/H-infinity control problem is formulated and solved for tracking control systems. The control problem, which combines H-2 and H-infinity performance criteria, can be applied to the design of compensators which achieve robust tracking performance in the presence of plant uncertainties. The optimal mixed H-2/H-infinity tracking controller has a separation property similar to those of linear quadratic and H-infinity tracking controllers, and its solution consists of an H-infinity-optimal state feedback tracking control problem and an associated mixed H-2/H-infinity-optimal estimation problem.