Illinois Health Partners serves over 100,000 HMO members in the western and southwestern suburbs of Chicago. The physician providers in Illinois Health Partners are located within the following service areas and beyond:
| Addison | Hinsdale | Oswego |
| Aurora | Homer Glen | Plainfield |
| Barlett | Joliet | Romeoville |
| Bloomingdale | LaGrange | Shorewood |
| Bolingbrook | Lemont | St. Charles |
| Carol Stream | Lisle | Warrenville |
| Crest Hill | Lockport | Westmont |
| Darien | Lombard | Wheaton |
| Downers Grove | Minooka | Willowbrook |
| Elmhurst | Naperville | Winfield |
| Geneva | Oakbrook | Woodridge |
| Glen Ellyn | Yorkville |