Swimming at the 2009 Southeast Asian Games – Women's 400 metre freestyle
# Swimming at the 2009 Southeast Asian Games – Women's 400 metre freestyle

The Women's 400 Freestyle swimming event at the 25th SEA Games was held on December 11, 2009.

## Results

### Final

| Place | Lane | Swimmer | Nation | Time | Notes |
| - | - | - | - | - | - |
| 1 | 4 | Cai Lin Khoo | Malaysia | 4:10.75 | GR |
| 2 | 5 | Lynette Lim | Singapore | 4:11.24 | |
| 3 | 6 | Ting Wen Quah | Singapore | 4:17.85 | |
| 4 | 3 | Rutai Santadvatana | Thailand | 4:19.10 | |
| 5 | 7 | Erica Totten | Philippines | 4:21.70 | |
| 6 | 8 | Wei Li Lai | Malaysia | 4:28.20 | |
| 7 | 2 | Benjaporn Sriphanomtorn | Thailand | 4:30.48 | |
| 8 | 1 | Raina Saumi | Indonesia | 4:30.74 | |

### Preliminary heats

| Rank | Heat/Lane | Swimmer | Nation | Time | Notes |
| - | - | - | - | - | - |
| 1 | H2 L5 | Cai Lin Khoo | Malaysia | 4:27.50 | Q |
| 2 | H1 L4 | Lynette Lim | Singapore | 4:27.78 | Q |
| 3 | H1 L5 | Erica Totten | Philippines | 4:28.00 | Q |
| 4 | H2 L4 | Ting Wen Quah | Singapore | 4:28.07 | Q |
| 5 | H1 L3 | Rutai Santadvatana | Thailand | 4:28.10 | Q |
| 6 | H2 L6 | Wei Li Lai | Malaysia | 4:29.71 | Q |
| 7 | H1 L6 | Raina Saumi | Indonesia | 4:29.95 | Q |
| 8 | H2 L3 | Benjaporn Sriphanomtorn | Thailand | 4:33.56 | Q |
| 9 | H2 L2 | Ressa Ressa | Indonesia | 4:36.85 | |
