Medina County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 50,748. Its county seat is Hondo. The county is named for the Medina River. The extreme northern part of the county lies within the Edwards Plateau, which elevates into the Texas Hill Country. The Medina Dam, the fourth largest in the nation when completed in 1913, is listed on the National Register of Historic Places. The irrigation project, creating Medina Lake, was built by 1500 skilled workers who worked in shifts operating 24 hours a day to complete the dam in two years. Medina County is part of the San Antonio, TX Metropolitan Statistical Area.

The Medina Dam is a hollow-masonry type dam built in 1911 and 1912 by the Medina Irrigation Company in what became Mico, Texas, USA. Medina Lake extends north of it in northeastern Medina County and southeastern Bandera County. The dam and irrigation project was designed and financed by Dr. Frederick Stark Pearson, an American engineer, with extensive British financial backing. The construction took over 1500 men two years to build while working 24 hours a day. They were mostly skilled Mexican workers with experience building other dams for Pearson. They received two dollars for a day's work, which were good wages for the time. Pearson's Medina Irrigation Company (MICO) built a camp to house the workers and their families; the company town was first called MICO after its acronym. The community is now known as Mico, Texas.