The Rienz river, near St. Lorenzen
Physical characteristics
 • locationSexten Dolomites
 • coordinates46°38′03″N 12°17′55″E / 46.63417°N 12.29861°E / 46.63417; 12.29861
 • elevation2,180 m (7,150 ft)
MouthEisack at Brixen
 • coordinates
46°42′46″N 11°39′38″E / 46.7129°N 11.6606°E / 46.7129; 11.6606Coordinates: 46°42′46″N 11°39′38″E / 46.7129°N 11.6606°E / 46.7129; 11.6606
Lengthapprox. 80 km (50 mi)
Basin features
ProgressionEisackAdigeAdriatic Sea

The Rienz (German pronunciation: [ˈriːɛnts] (About this soundlisten); Italian: Rienza [riˈɛntsa]) is a river in South Tyrol, Italy. Its source is located at 2,180 m of altitude, in the Dolomites mountains, south of Toblach: near Toblach it enters in the Puster Valley, and, after 90 km (56 mi), it meets the Eisack river in the city of Brixen, at 550 m of altitude.

The Rienz flows through the following municipalities (source to mouth): Toblach, Niederdorf, Welsberg-Taisten, Olang, Rasen-Antholz, Bruneck, St. Lorenzen, Kiens, Vintl, Mühlbach, Rodeneck and Brixen.

The most significant affluents are:

The maximum discharge of the Rienz is around 60 m³/s.