Abstract: This paper describes a real-time system supporting a tele-surgery application based on the ZeusTM system. The application involves performing minimally- invasive surgical procedures remotely?i.e. without the surgeon present in the same room with the patient. Because there is human life at stake, the underlying real-time system must be robust, fail-safe, and resilient to communications problems. This paper focusses primarily on the approach taken in communicating between the surgeon-side and patient-side subsystems. In particular, techniques for dealing with the challenges of real-time communications are discussed, e.g. bit- errors, packet errors, synchronization. In addition to the control actions and feedback data several serial data streams are multiplexed, transmitted between one side and the other, demultiplexed, and delivered by the real- time system. These streams have a fundamentally different character from the control actions and feedback values used with the robots. Both types of real-time streams are sent over the same communications link.TM