IROC XXIII was the twenty-third season of IROC, the (International Race Of Champions), which started on February 12, 1999. The series used identically prepared Pontiac Firebird Trans Am race cars, and the contested races were held at Daytona International Speedway, Talladega Superspeedway, Michigan International Speedway, and Indianapolis Motor Speedway. Dale Earnhardt won the first three races of the season, including two last lap passes at Daytona and Talladega, and beating his son Dale Earnhardt Jr. at Michigan in a photo finish, to win the championship and $225,000.
The roster of drivers and final points standings were as follows:
| Position | Driver | Points | Winnings | Series | |
|---|---|---|---|---|---|
| 1 | 75 | $225,000 | NASCAR Winston Cup | ||
| 2 | 74 | $100,000 | NASCAR Winston Cup | ||
| 3 | 53 | $60,000 | NASCAR Winston Cup | ||
| 4 | 50 | $50,000 | NASCAR Winston Cup | ||
| 5 | 49 | $45,000 | NASCAR Winston Cup | ||
| 6 | 34 | $40,000 | Indy Racing League | ||
| 7 | 31 | $40,000 | Indy Racing League | ||
| 8 | 30 | $40,000 | NASCAR Winston Cup | ||
| 9 | 29 | $40,000 | NASCAR Busch Series | ||
| 10 |  Adrian Fernandez1 | 28 | $40,000 | FedEx CART World Series | |
| 11 | 26 | $40,000 | NASCAR Winston Cup | ||
| 12 | 25 | $40,000 | FedEx CART World Series |