The 129th Regiment Illinois Volunteer Infantry was an American infantry regiment that served in the Union Army during the American Civil War.

The 129th Illinois Infantry was organized at Pontiac, Illinois, and mustered into Federal service on September 8, 1862, for a three-year enlistment.

The regiment was mustered out of service on June 8, 1865.

The regiment suffered 50 enlisted men who were killed in action or who died of their wounds and 2 officers and 128 enlisted men who died of disease, for a total of 180 fatalities.

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