Altleiningen is an Ortsgemeinde – a municipality belonging to a Verbandsgemeinde, a kind of collective municipality – in the Bad Dürkheim district in Rhineland-Palatinate, Germany.

The municipality lies at an elevation of 300 m above sea level in the northeast Palatinate Forest in the valley of the Eckbach, a 39 km-long brook that empties into the Rhine. Altleiningen belongs to the Verbandsgemeinde of Leiningerland, whose seat is in Grünstadt.

Altleiningen, originally Leiningen, had its first documentary mention in 780 when the 50 km-distant Lorsch Abbey’s catalogue of holdings listed a woodland holding in linunga marca (Latin for “in the Leiningen area”). The naming referred to the Leinbaum, a name used locally at the time mostly for the Norway Maple, but sometimes also for the large-leaved linden. Since both trees were often found growing alongside the Eckbach, the brook at this time also went by the name Leinbach.

From the municipality's name also sprang the noble family Leiningen’s name. This family held the so-called Leiningerland for centuries.

After the Second World War, the municipality belonged at first to the Frankenthal district, which in the course of administrative reform in Rhineland-Palatinate was abolished in 1969. Altleiningen then found itself in the newly created district of Bad Dürkheim. In 1972, Altleiningen also found itself in the likewise newly created Verbandsgemeinde of Hettenleidelheim.

In 2007, 45.7% of the inhabitants were Evangelical and 30.1% Catholic. The rest belonged to other faiths or adhered to none.

The municipal election held on 7 June 2009 yielded the following results:

The German blazon reads: In Rot ein schwebendes angetatztes goldenes Kreuz mit eingeschlagenen eichenblattartigen Verzierungen an den Balkenenden, bewinkelt von vier silbernen Adlern.