Eustis is a city in Lake County, Florida, United States. The population was 15,106 at the 2000 census. The Census Bureau estimated the population in 2008 to be 19,129. It is part of the OrlandoKissimmeeSanford Metropolitan Statistical Area. Eustis is located at 285104N814055W / 28.850993N 81.681943W / 28.850993; -81.681943.