Rio Medina, is an unincorporated community in Medina County, Texas, United States. It is located approximately five miles north of Castroville and is part of theSan Antonio Metropolitan Statistical Area. According to the 2006-07 Texas Almanac, it had a population of 60 people in 2000. According to an online community profile, Rio Medina has a population of 541 people (population year not provided). The town is located on the Medina River and is several miles south of Medina Lake.