The following NASCAR national series were held in 2003:
- 2003 NASCAR Winston Cup Series - The top racing series in NASCAR.
- 2003 NASCAR Busch Series - The second-highest racing series in NASCAR.
- 2003 NASCAR Craftsman Truck Series - The third-highest racing series in NASCAR.
| Preceded by2002 in NASCAR | NASCAR seasons 2003 |
Succeeded by2004 in NASCAR |