This is a list of high schools in the U.S. state of Illinois.

Adams County

Quincy

Alexander County

Bond County

Boone County

Belvidere

Brown County

Bureau County

Calhoun County

Carroll County

Cass County

Champaign County

Champaign

Urbana

Christian County

Clark County

Clay County

Clinton County

Breese

Coles County

Cook County

Arlington Heights

Bridgeview

Burbank

Chicago Public Schools

Chicago Independent Schools

Archdiocese of Chicago (Chicago/Cook County)

Chicago Heights

Des Plaines

Evanston

Hoffman Estates

Lansing

Niles

Oak Lawn

Palatine

Palos Heights

Park Ridge

Richton Park

Skokie

Tinley Park

Winnetka

Defunct

Crawford County

Cumberland County

DeKalb County

DeWitt County

Douglas County

DuPage County

Aurora

Downers Grove

Elmhurst

Glen Ellyn

Lisle

Lombard

Naperville

Villa Park

Wheaton

West Chicago

Defunct

Edgar County

Edwards County

Effingham County

Effingham

Fayette County

Ford County

Franklin County

Fulton County

Gallatin County

Greene County

Grundy County

Hamilton County

Hancock County

Hardin County

Henderson County

Henry County

Kewanee

Iroquois County

Defunct

Jackson County

Carbondale

Jasper County

Jefferson County

Jersey County

Jo Daviess County

Johnson County

Kane County

Aurora

Elgin

St. Charles

Defunct

Kankakee County

Kankakee

Kendall County

Oswego

Knox County

LaSalle County

Ottawa

Lake County

Grayslake

Lake Forest

Mundelein

Waukegan

Zion

Defunct

Lawrence County

Lee County

Livingston County

Logan County

Macon County

Decatur

Defunct

Macoupin County

Madison County

Alton

Edwardsville

Defunct

Marion County

Marshall County

Mason County

Massac County

McDonough County

McHenry County

Crystal Lake

Woodstock

McLean County

Bloomington

Normal

Menard County

Mercer County

Monroe County

Waterloo

Montgomery County

Morgan County

Jacksonville

Moultrie County

Ogle County

Peoria County

Peoria

Defunct

Perry County

Piatt County

Pike County

Pope County

Pulaski County

Putnam County

Randolph County

Richland County

Rock Island County

St. Clair County

Belleville

East St. Louis

Saline County

Sangamon County

Springfield

Defunct

Schuyler County

Scott County

Shelby County

Stark County

Stephenson County

Freeport

Tazewell County

Union County

Vermilion County

Danville

Defunct

Wabash County

Warren County

Washington County

Wayne County

White County

Whiteside County

Will County

Crete

Joliet

New Lenox

Plainfield

Defunct

Williamson County

Johnston City

Marion

Winnebago County

Rockford

Defunct

Woodford County