The 85th Regiment Illinois Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War.

The 85th Illinois Infantry was organized at Peoria, Illinois and mustered into Federal service on August 27, 1862.

The regiment was mustered out on June 5, 1865.

The regiment suffered 4 officers and 86 enlisted men who were killed in action or who died of their wounds and 1 officers and 131 enlisted men who died of disease, for a total of 222 fatalities.

This article about a specific military unit of the American Civil War is a stub.