Ruta Nacional 3 ("National Route 3") is an Argentine highway, stretching from the eastern side of the country in Buenos Aires, crossing the provinces of Buenos Aires, Río Negro, Chubut Province, Santa Cruz and Tierra del Fuego. Since its start at Avenida General Paz (A001) until the end, on the bridge over Lapataia River, it measures 3,045 kilometres (1,892 mi).

The road is interrupted between km 2674 and 2696, due to the presence of Magellan Strait, which forces access between Santa Cruz and Tierra del Fuego Provinces through Chile, over Ruta CH-255 and Ruta CH-257 paved 57 kilometres (35 mi) north of the strait and another paved and treated 148 kilometres (92 mi) long south of it. The crossing of the Magellan Strait is done in 20 minutes through the use of a ferry traversing the width of 4.65 kilometres (2.89 mi) at that point.

After National Decree 1931 of 3 August 1983, this road is called Comandante Luis Piedrabuena south of National Route 22, that is starting at km marker 719.