Addison Trail High School (ATHS) is a public four-year high school in DuPage County, located approximately half a mile east of Interstate 355 at the intersection of Army Trail Road and Lombard Road in Addison, Illinois, a western suburb of Chicago, Illinois, in the United States. It is part of DuPage High School District 88 (originally Addison District #4), which also includes Willowbrook High School.