Rio Medina or Riomedina is an unincorporated community in Medina County, Texas, United States. It is located approximately six miles north of Castroville and is part of the San 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.