The 138th Field Artillery Brigade is a field artillery brigade of the United States Army. It is a component of the Kentucky Army National Guard. It is headquartered in Lexington, Kentucky.

The Kentucky Army National Guard is a component of the United States Army and the United States National Guard. Nationwide, the Army National Guard comprises approximately one half of the US Army's available combat forces and approximately one third of its support organization. National coordination of various state National Guard units are maintained through the National Guard Bureau.