This document summarizes health service support (HSS) operations in the Marine Corps. It outlines the mission of HSS units to minimize the effects of wounds and illness on readiness. The HSS system is established through preventive medicine programs and support networks at the Marine Expeditionary Force, Marine Division, Marine Aircraft Wing, and Marine Logistics Group levels. Medical staff at each level are responsible for HSS requirements and support may come from casualty receiving ships, fleet hospitals, or other service medical facilities as needed.