The 2nd Battalion, 503rd Infantry Regiment (2-503rd IR) is an active duty airborne infantry battalion in the United States Army, assigned to the 173rd Airborne Brigade Combat Team and stationed at Caserma Del Din, Vicenza, Italy.

The lineage of Company B, 503rd AIR was redesignated on 1 September 1957 as Headquarters and Headquarters Company, 2d Airborne Battle Group, 503d Infantry (2-503rd), assigned to the 82nd Airborne Division, and activated at Fort Bragg, North Carolina (organic elements concurrently constituted and activated).

From December 1986 to September 1990, the 2-503rd was assigned to Camp Hovey, Korea, along with the 1-503rd, as a Light Infantry battalion.

While there the battalion participated in annual rotations for patrol, guardpost, and quick-reaction force duty at the DMZ.

Note: The published Army lineage shows War on Terrorism "Campaigns to be determined".