| Rio dos Sinos | |
| Pushpin Map: | Brazil |
| Source1 Location: | Rio Grande do Sul state |
| Source1 Elevation: | 695m (2,280feet) |
| Mouth Location: | Canoas |
| Mouth Coordinates: | -29.9344°N -51.2358°W |
| Mouth Elevation: | 5m (16feet) |
| Basin Size: | 3820km2 |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
| Length: | 190km (120miles) |
Rio dos Sinos is a river in the state of Rio Grande do Sul, southern Brazil. It rises in the hills east of Caraá (away from Porto Alegre) at elevations above and covers a distance of about, flowing into the delta Jacuí in Canoas, at an elevation of only .
The river basin contains the São Francisco de Paula National Forest, a 1616ha sustainable use conservation area created in 1968.