Rüfenach is a municipality in the district of Brugg in the canton of Aargau in Switzerland.
The municipality lies at the foot of the Bruggerberg and the Reinerberg, the southeast foothills of the Jura Mountains.
It consists of three villages, Rüfenach, Hinterrein, and Vorderrein. The latter two were part of an independent municipality called Rein until 1898.. Rüfenach lies furthest west in the middle of a flat plain. Hinterrein is slightly higher and lies in the middle. Vorderrein is to the east on a marked hill. The east side of this hill falls sharply to the Aare. The difference in altitude is about 70 m (230 ft).
Rüfenach has an area, as of 2009, of 4.17 square kilometers (1.61 sq mi). Of this area, 1.98 square kilometers (0.76 sq mi) or 47.5% is used for agricultural purposes, while 1.7 square kilometers (0.66 sq mi) or 40.8% is forested. Of the rest of the land, 0.48 square kilometers (0.19 sq mi) or 11.5% is settled (buildings or roads), 0.02 km2 (4.9 acres) or 0.5% is either rivers or lakes.