| Unit Name: | 4th Connecticut Volunteer Infantry |
| Dates: | May 21, 1861 - January 2, 1862 |
| Country: | United States |
| Allegiance: | Union |
| Branch: | United States Army |
| Type: | Infantry |
| Command Structure: | 6th Brigade (Abercrombie's), 2nd Division, Department of Pennsylvania |
| Battles: | American Civil War |
| Commander1: | Levi Woodhouse |
| Commander1 Label: | Colonel |
| Commander2: | Robert O. Tyler |
| Commander2 Label: | Colonel |
The 4th Connecticut Infantry Regiment was an infantry regiment that served in the Union Army during the American Civil War.
The 4th Connecticut Infantry Regiment was organized at Hartford, Connecticut and mustered in on May 21, 1861.
The regiment was attached to Abercrombie's 6th Brigade, 2nd Division, Department of Pennsylvania, to August 1861. 2nd Brigade, Banks' Division, Army of the Potomac, to December 1861. Defenses of Washington to January 1862.
The 4th Connecticut Infantry ceased to exist when its designation was changed to 1st Connecticut Heavy Artillery on January 2, 1862.
Left Connecticut for Washington, D.C., June 10. Duty at Chambersburg, Pennsylvania, and at Hagerstown, Maryland, until July 4, 1861, and at Williamsport until August 16. At Frederick, Maryland, until September 5. Moved to Darnestown September 5, then to Fort Richardson. Service in the Defenses of Washington, D.C., and duty there until January 1862.