The Aalenian is a subdivision of the Middle Jurassic epoch of the geologic timescale that extends from about 175.6 Ma to about 171.6 Ma (million years ago). It was preceded by the Toarcian era and succeeded by the Bajocian.
The stage takes its name from the town of Aalen, some 100 km east of Stuttgart in Germany. The town lies at the southwestern end of the Frankischer Jura.
| Hettangian | Sinemurian Pliensbachian | Toarcian |
Aalenian | Bajocian Bathonian | Callovian |
Oxfordian | Kimmeridgian Tithonian |