The 45th Wisconsin Infantry Regiment was a volunteer infantry regiment that served in the Union Army during the American Civil War.

The 45th Wisconsin was organized at Madison, Wisconsin, and mustered into Federal service on November 8, 1864.

It was assigned to the garrison of Nashville, Tennessee, for its entire service.

The 45th Wisconsin suffered 34 enlisted men who died of disease, for a total of 34 fatalities.

This article about a specific military unit of the American Civil War is a stub.