Lower Isenburg Nieder-Isenburg
1218 (1199) - 1503
Capital Circle Bench	Isenburg Lower Rhenish-West. Counts of Wetterau
Partitioned from Isenburg-Isenburg	1218 (1199)
Partitioned	1502
Extinct	1503

Lower Isenburg (German: Nieder-Isenburg) was the name of a state of the Holy Roman Empire, based around Isenburg in modern Rhineland-Palatinate, Germany.

The County of Lower Isenburg emerged as a partition of Isenburg-Isenburg in 1218 (1199). Lower Isenburg was informally mediate to the Abbey of Fulda, although the claim was not pursued for centuries. The Isenburgs were one of the oldest families in the Westerwald and despite partitioning into several lines Lower Isenburg was the residence of choice for those in the Rhineland. In 1502 Lower Isenburg was partitioned into Isenburg-Grenzau and Isenburg-Neumagen. Isenburg-Neumagen became extinct in 1554 and Isenburg-Grenzau in 1664, and the Counts of Wied and the barons of Walderdorff divided the County between them.

Name	Reign
Theodoric I	1218 - 1253
Theodoric II	1253 - 1273
Salentin I	1273 - c1300
Salentin II	1300 - 1334
Salentin III	1319 - 1370
Salentin IV	1370 - c1420
Salentin V	c1420 - 1458
Gerlach I	1458 - 1490
James	1486 - 1503
Gerlach II	1490 - 1502