Sardis is a census-designated place (CDP) in southeastern Lee Township, Monroe County, Ohio, United States. It is unincorporated, but has a post office with the ZIP code of 43946. As of the 2010 census, it had a population of 559.Sardis is at the intersection of Ohio State Routes 7 and 255. An Ohio River town, it lies below Hannibal and above New Matamoras.Sardis shares a consolidated high school, River High School, with Antioch, Duffy, Fly, Hannibal, Laings, Powhatan Point, and Clarington.