21st Illinois Volunteer Infantry Regiment

21st Regiment Illinois Volunteer Infantry
Illinois state flag
Active	June 28, 1861 to December 16, 1865
Country	United States
Allegiance	Union
Branch	Infantry

The 21st Regiment Illinois Volunteer Infantry was a militia infantry regiment that served in the Union Army during the American Civil War.

The 21st Illinois Infantry was organized at Mattoon, Illinois and mustered into Federal service on June 28, 1861.

The regiment was mustered out on December 16, 1865.

The regiment suffered 1 officer and 51 enlisted men who were killed in action or who died of their wounds and 2 officers and 127 enlisted men who died of disease, for a total of 181 fatalities.