The 86th Regiment Illinois Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War.

The 86th Illinois Infantry was organized at Peoria, Illinois and mustered into Federal service on August 27, 1862.

The regiment was mustered out on June 6, 1865, and discharged at Chicago, Illinois, on June 21, 1865.

The regiment suffered 3 officers and 73 enlisted men who were killed in action or who died of their wounds and 1 officers and 93 enlisted men who died of disease, for a total of 175 fatalities.

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