Altenhaßlau is a village in Linsengericht in the Main-Kinzig district of Hesse, Germany. It is located in the valley of the Kinzig, south and southeast of the town of Gelnhausen. Linsengericht also consists of the villages of Eidengesäß, Geislitz (with Hof Eich and Eichermühle), Großenhausen (with Waldrode) and Lützelhausen.
Altenhaßlau has a population of over 3,650 people. Altenhaßlau also forms part of the wider Linsengericht area which has a population of over 9,886 people.