Altenau is a town in Lower Saxony.
Altenau may also refer to:
- Altenau (Oker), a tributary of the Oker in eastern Lower Saxony
- Altenau (Alme), a tributary of the Alme in eastern North Rhine-Westphalia
- Altenau, a part of Mühlberg, Brandenburg, Germany
People with the surname
- Cornelis Altenau (died 1558), Danish-German builder
See also
- Altnau
- Altena (disambiguation)
- Altona (disambiguation)