Ishme-Dagan I is the son of the Assyrian king Shamshi-Adad I, put on throne of Ekallatum by his father after a successful military attack.

He rules the area of the upper Tigris, including the city-state of Assur.

Following Shamshi-Adad's death (in the 17th year of Hammurabi of Babylon), Ishme-Dagan I manages to rule Assyria until himself being ousted by Hammurabi.

The much later Assyrian kinglist credited Ishme-Dagan with 40 years, but it is now known, from a recently (2003) discovered limmu-list of eponyms unearthed at Kanesh, that his reign in Assur lasted 11 years.

His brother, Yasmah-Adad, rules around the same time in the city of Mari, where the correspondence between the father and two sons was found by archaeologists.