Centegra Health System was a system of health care providers in McHenry County, Illinois, United States. It comprised three hospitals, two fitness centers, four immediate care centers, nearly a dozen physician care locations and numerous specialty care services. In 2013, the system had over 4,000 employees and 500 volunteers, and 460 physicians. On September 1, 2018, Centegra was acquired by Northwestern Medicine of Chicago, Illinois. Prior to its acquisition, Centegra was the largest independent employer in McHenry County.