Saint-Ouen-d'Aunis (First part, French meaning Saint Owen) is a commune in the canton of Marans in the Charente-Maritime department in the Poitou-Charentes region in western France.
| Year | Population | Density | Percent of the canton |
|---|---|---|---|
| 1962 | 209 | - | - |
| 1968 | 246 | - | - |
| 1975 | 339 | - | - |
| 1982 | 524 | - | - |
| 1990 | 612 | - | - |
| 1999 | 692 | 78/km² | - |