| Unit Name: | 11th New Hampshire Infantry Regiment |
| Country: | United States of America |
| Allegiance: | New Hampshire & Union |
| Type: | Volunteer infantry |
| Dates: | September 24, 1862 - June 4, 1865 |
| Battles: | |
| Notable Commanders: | Walter Harriman |
The 11th New Hampshire Infantry Regiment was a Union army infantry regiment that participated in the American Civil War. It was raised in the New England state of New Hampshire, serving from October 4, 1862, to June 4, 1865.
On September 2, 1862, the regiment was organized and mustered in at Concord, New Hampshire. Among its notable officers was Walter Harriman, a future Governor of New Hampshire.
From September 11 to 14, 1862, the 11th moved to Washington, D.C. It was attached to Briggs' Brigade, Casey's Division, Military District of Washington, until October 1862, and then to the 2nd Brigade, 2nd Division, 9th Army Corps, Army of the Potomac, until March 1863. From then, its assignments were:
The regiment lost during its term of service 5 officers and 140 enlisted men killed and mortally wounded, and 1 officer and 151 enlisted men by disease, for a total of 297 fatalities.