Ilam County (Persian: شهرستان ایلام) is in Ilam Province, Iran. Its capital is the city of Ilam.

After the 2011 National Census, Keshvari Rural District was created in the Central District, and Mish Khas Rural District was separated from it in the formation of Sivan District, including the new Alishervan Rural District.

In 2019, the village of Jafarabad was elevated to the status of a city. Chavar District was separated from the county in the establishment of Chavar County.

In 2023, Mahmudabad Rural District was created in Sivan District, and Alishervan Rural District was separated from it to join Badreh County.

At the time of the 2006 census, the county's population was 193,222 in 42,207 households. The following census in 2011 counted 213,579 people in 52,391 households. The 2016 census measured the population of the county as 235,144 in 64,671 households.

Ilam County's population history and administrative structure over three consecutive censuses are shown in the following table.

Media related to Ilam County at Wikimedia Commons