4th Illinois Volunteer Infantry Regiment was an infantry regiment of the United States Volunteers that served in the United States Army during the Mexican–American War and Spanish–American War.

It was under the command of Colonel Edward D. Baker.

At the Battle of Cerro Gordo, the regiment surprised the command of General Santa Anna, capturing his wooden leg.

During the Spanish–American War the regiment served as part of the occupation forces in Cuba.

This article about a specific American military unit is a stub.