Doña Ana County (Spanish: Condado de Doña Ana) is a county located in the southern part of the New Mexico, United States. As of the 2020 U.S. census, its population was 219,561, which makes it the second-most populated county in New Mexico. Its county seat is Las Cruces, which has a population of 111,385 as of the 2020 U.S. Census, making it the second-most populous municipality in New Mexico after Albuquerque.
The county is named for Doña Ana Robledo, who died there in 1680 while fleeing the Pueblo Revolt.