Piedras Negras is a city and seat of the surrounding municipality of the same name in the Mexican state of Coahuila. It stands at the northeastern edge of Coahuila on the U.S.-Mexico border, across the Río Bravo (Rio Grande) from Eagle Pass in the U.S. state of Texas.

In the 2005 census the city Piedras Negras had a population of 142,011 people, which accounted for 98.6 percent of its municipality's total population of 143,915. The municipality's area is relatively small, but does include some outlying minor localities not located inside the city limits.

The Eagle Pass and Piedras Negras area is connected by the Eagle Pass-Piedras Negras International Bridge, Camino Real International Bridge, and the Eagle Pass Union Pacific International Railroad Bridge.