Mercy Health Fairfield (Ohio) Hospital. Fairfield Hospital serves patients in Butler County and is part of Cincinnati-based Mercy Health. The 192-bed hospital was named one of the 100 Top Hospitals and one of the 50 Top Cardiovascular Hospitals in 2014 by Truven Health Analytics. In 2015, iVantage named Fairfield a HealthStrong Top Hospital and Healthgrades recognized the hospital with awards in patient safety and patient experience, overall clinical excellence and excellence in five specialties.