The 2003 Chicagoland 100 was Round 10 of the 2003 IRL Infiniti Pro Series. The event was held at Chicagoland Speedway in Illinois, United States on 6 September 2003. Mark Taylor was the race winner.
Chicagoland 100 Race Result
| Pos. | No. | Driver | Chassis | Engine | Tire | Laps | Laps Led | Status | Started | Points |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 4 | Mark Taylor | Dallara | Infiniti | Firestone | 67 | 11 | Running | 2 | 50 |
| 2 | 14 | Ed Carpenter | Dallara | Infiniti | Firestone | 67 | 56 | Running | 1 | 42 |
| 3 | 20 | Jeff Simmons | Dallara | Infiniti | Firestone | 67 | 0 | Running | 13 | 35 |
| 4 | 5 | Arie Luyendyk Jr. | Dallara | Infiniti | Firestone | 67 | 0 | Running | 4 | 32 |
| 5 | 91 | Aaron Fike | Dallara | Infiniti | Firestone | 67 | 0 | Running | 3 | 30 |
| 6 | 92 | Cory Witherill | Dallara | Infiniti | Firestone | 67 | 0 | Running | 7 | 28 |
| 7 | 25 | G.J. Mennen | Dallara | Infiniti | Firestone | 67 | 0 | Running | 5 | 26 |
| 8 | 27 | Gary Peterson | Dallara | Infiniti | Firestone | 67 | 0 | Running | 8 | 24 |
| 9 | 36 | Thiago Medeiros | Dallara | Infiniti | Firestone | 67 | 0 | Running | 6 | 22 |
| 10 | 3 | Marty Roth | Dallara | Infiniti | Firestone | 66 | 0 | Running | 11 | 20 |
| 11 | 24 | Billy Roe | Dallara | Infiniti | Firestone | 61 | 0 | Running | 12 | 19 |
| DNF | 99 | Marco Cioci | Dallara | Infiniti | Firestone | 55 | 0 | Accident | 10 | 18 |
| DNF | 33 | Paul Dana | Dallara | Infiniti | Firestone | 16 | 0 | Accident | 14 | 17 |
| DNF | 9 | Taylor Fletcher | Dallara | Infiniti | Firestone | 7 | 0 | Gearbox | 9 | 16 |