The following companies have locations within the Chicago city limits:

• Accenture HQ Website
• Aon HQ (Ranked #199 on the Fortune 500) Website
• Baird & Warner HQ
• Bank One HQ (Ranked #88 on the Fortune 500)
• Baxter International
• Boeing HQ (Ranked #21 on the Fortune 500)
• Brunswick Corporation HQ
• CDW HQ
• Chess Records
• Chicago Board of Trade HQ
• Chicago Mercantile Exchange HQ
• Chicago Stock Exchange HQ
• Click Commerce HQ
• CNA Financial HQ
• Encyclopædia Britannica
• Equity Office Properties HQ (Ranked #493 on the Fortune 500)
• Equity Residential Properties Trust HQ
• Exelon HQ (Ranked #126 on the Fortune 500)
• Fortune Brands
• General Growth Properties HQ
• Grainger HQ
• Hostway
• Illinois Tool Works HQ
• Molex
• Morton Salt HQ
• Motorola HQ
• Music Corporation of America
• National Stock Exchange
• Navistar International
• Newell Rubermaid
• Nicor
• Northern Trust HQ
• Old Republic International Corporation HQ (Ranked #491 on the Fortune 500)
• Orbitz HQ
• Peoples Energy HQ
• Playboy HQ
• Quaker Oats
• R.R. Donnelley & Sons HQ (Ranked #362 on the Fortune 500)
• Rotary International
• Sara Lee HQ (Ranked #104 on the Fortune 500) Website
• Servicemaster
• Smurfit-Stone Container Corporation HQ (Ranked #255 on the Fortune 500)
• Telephone and Data Systems Incorporated HQ (Ranked #480 on the Fortune 500)
• Tribune Company HQ (Ranked #323 on the Fortune 500)
• US Cellular HQ
• USG Corporation HQ (Ranked #458 on the Fortune 500)
• Unitrin
• Whittman-Hart HQ Website
• WM. Wrigley Jr. Company HQ Website

The following companies are based in Chicago's suburbs:

• Abbott Laboratories (North Chicago, IL)
• Allstate (Northbrook, IL)
• Azteca Foods (Summit-Argo , IL)
• ComDisco (Rosemont, IL)
• ConAgra (Downers Grove, IL)
• Kraft Foods (Northfield, IL)
• McDonald's Corporation (Oak Brook, IL)
• Motorola (Schaumburg, IL)
• Sears (Hoffman Estates, IL)
• Tellabs (Naperville, IL)
• United Airlines (Elk Grove Village, IL)
• Walgreens (Deerfield, IL)

There are other large corporations with an established presence in Chicago's suburbs (but whose corporate headquarters are located elsewhere), including:

• BP
• Lucent Technologies
• UPS