Oppenau (German: [ˈɔ.pə.naʊ̯] ⓘ) is a city located in the state of Baden-Württemberg, Germany.

Oppenau is situated in the Rench valley in the Black Forest.

In the 12th century an agricultural settling made up the village Noppenouwe, which succumbed to the House of Zähringen until 1218.

The in 1192 in Lierbach founded All Saints’ Abbey took a high political, cultural and religious influence to Oppenau at this time.

In 1990, German politician Wolfgang Schäuble suffered an assassination attempt in Oppenau.