The 8th Indiana Cavalry Regiment was a cavalry regiment from Indiana that served in the Union Army during the American Civil War.

After being converted to mounted infantry, the regiment served in the Tullahoma campaign and at Chickamauga.

On October 15, 1863, the unit was renamed the 8th Indiana Cavalry and took part in Rousseau's Opelika Raid, and fought at Brown's Mill and Lovejoy's Station in the Atlanta campaign.

The regiment served in Sherman's March to the Sea and the Carolinas campaign before being mustered out of service on July 20, 1865.

Organized at Indianapolis, Ind., as 39th Regiment Infantry, August 29, 1861.

Ordered to Kentucky and duty at Muldraugh's Hill, Camp Nevin, Nolin Creek and Green River until February, 1862.

Attached to Wood's Brigade, McCook's Command, at Nolin, Army of the Ohio, October–November, 1861.

6th Brigade, 2nd Division, Army of the Ohio, to September, 1862.

Unassigned Cavalry Corps, Army of the Cumberland, to October, 1863.

1st Brigade, 2nd Division, Cavalry Corps, Army of the Cumberland, to April, 1864.

2nd Brigade, Kilpatrick's 3rd Division, Cavalry Corps, Army of the Cumberland, to October, 1864.

Buell's Campaign in Northern Alabama and Middle Tennessee June to August.

March to Nashville, Tenn.; thence to Louisville, Ky., in pursuit of Bragg August 20-September 26.

March to Bowling Green, Ky.; thence to Nashville, Tenn., October 16-November 7, and duty there until December 26.

Battle of Stone's River December 30–31, 1862, and January 1–3, 1863.

Passage of Cumberland Mountains and Tennessee River and Chickamauga (Ga.) Campaign August 16-September 22.

Davis Ford, Chickamauga Creek, September 17.

Expedition to East Tennessee after Champ Ferguson September–October.

Designation changed from 39th Infantry to 8th Cavalry October 15, 1863.

Ten Island Ford, Coosa River, Ala., July 14.

McCook's Raid to Atlanta & West Point R. R. July 27–31.

Camp Creek and Flint River Station August 30.

Buckhead Creek (or Reynolds' Plantation) November 28.

[2] Regiment lost during service 9 Officers and 138 Enlisted men killed and mortally wounded and 1 Officer and 250 Enlisted men by disease.