The 2003 Jersey Flegg season was a shortened 12-week competition that ran alongside the SG Ball Cup. It used an under-19 format before reverting back to a full, under-20 season in 2004.
| Results | Finals Results |
Premiers: Canterbury Bulldogs (9th title)
Runners-up: Cronulla Sharks
Minor Premiers: Cronulla Sharks
| Team | P | W | D | L | B | F | A | PD | Pts | |
| 1 | Cronulla Sharks | 8 | 7 | 0 | 1 | 1 | 239 | 145 | 94 | 16 |
| 2 | Western Suburbs Magpies | 8 | 7 | 0 | 1 | 1 | 261 | 160 | 101 | 16 |
| 3 | Canterbury Bulldogs | 8 | 6 | 0 | 2 | 1 | 288 | 164 | 124 | 14 |
| 4 | Parramatta Eels | 8 | 5 | 0 | 3 | 1 | 188 | 164 | 24 | 12 |
| 5 | Canberra Raiders | 8 | 4 | 1 | 3 | 1 | 260 | 174 | 86 | 11 |
| 6 | Newcastle Knights | 8 | 4 | 1 | 3 | 1 | 238 | 169 | 69 | 11 |
| 7 | Balmain Tigers | 8 | 4 | 1 | 3 | 1 | 220 | 172 | 48 | 11 |
| 8 | Illawarra Steelers | 8 | 4 | 0 | 4 | 1 | 214 | 146 | 68 | 10 |
| 9 | Manly Sea Eagles | 8 | 4 | 0 | 4 | 1 | 206 | 214 | -8 | 10 |
| 10 | Sydney Roosters | 8 | 4 | 0 | 4 | 1 | 228 | 246 | -18 | 10 |
| 11 | Penrith Panthers | 8 | 3 | 0 | 5 | 1 | 198 | 204 | -6 | 8 |
| 12 | South Sydney Rabbitohs | 8 | 3 | 0 | 5 | 1 | 236 | 265 | -29 | 8 |
| 13 | North Sydney Bears | 8 | 2 | 0 | 6 | 1 | 146 | 188 | -42 | 6 |
| 14 | St George Dragons | 8 | 1 | 1 | 6 | 1 | 144 | 262 | -118 | 5 |
| 15 | Central Coast Rip | 8 | 0 | 0 | 8 | 1 | 66 | 458 | -392 | 2 |
18TH MAN 