Results of a comparison study of the tracking accuracy of two commercially available wide-range position tracking systems suitable for CAVEs are presented. An experiment was conducted with Flock of Birds and IS-900 tracking systems installed in the same CAVE environment to compare their accuracy. Another experiment was performed with a newly deployed IS-900 to investigate the impact of different ultrasound emitter configurations on the accuracy of the location tracking. The results show that the IS-900 has a much better accuracy over a larger range of operation than does the Flock of Birds; however, it is sensitive to the optimality of the ultrasound emitters configuration.