Recent advances in human motion capture and head mounted display technologies, coupled with Distributed Interactive Simulation (DIS) capabilities, now allow for the implementation of an untethered, fully-immersable, DIS-compliant, real-time Dismounted Soldier Simulation (DSS) System. The untethered soldier, outfitted with a set of optical markers and a wireless helmet-mounted display, can move about freely within a real-world motion capture area, while position and orientation data are gathered and sent onto a DIS network via tracking cameras and image processing computers. The soldier's interaction in the virtual environment includes the ability to move within the battlefield unencumbered by wires or other peripheral devices, fire an M16A2 rifle, hear DIS battlefield audio, and communicate with other entities via a DIS radio simulator. Fully articulated human motion rotations and translations are sent onto the DIS network using Entity State and Data PDUs. Along with position and orientation information, the dismounted soldier's discrete state is transmitted in the Entity State PDU appearance field so that all receiving entities know what the virtual soldier is doing (i.e., running, walking, or crawling). Data PDUs are sent out with the real-time motion information so that simulations interested in displaying an articulated human figure know how the figure is moving. The Data PDUs are 288 bytes in length and are sent out at a frequency of 1 to 30 per second. When the soldier pulls the trigger on the M16A2, a wireless signal is sent to the host computer, which generates Fire and Detonation PDUs. Data has been captured and analyzed in the following areas: motion capture accuracy, transport delay, latency, image refresh rate, bandwidth usage, firing accuracy, and simulator sickness.