| River Cain | |
| Pushpin Map: | Wales Powys |
| Pushpin Map Caption: | Location of the mouth within Powys |
| Subdivision Type1: | Country |
| Subdivision Name1: | Wales |
| Subdivision Type3: | Counties |
| Subdivision Name3: | Powys |
| Length: | 16km (10miles) |
| Source1: | Confluence of Nant Alan and Nant Fyllon |
| Source1 Coordinates: | 52.7706°N -3.2837°W |
| Mouth Location: | River Vyrnwy |
| Mouth Coordinates: | 52.774°N -3.147°W |
| Tributaries Left: | Nant Fyllon, River Abel, Nant Llys |
| Tributaries Right: | Nant Alan, The Brogan |
The River Cain (Afon Cain in Welsh) is a river in north Powys which flows into the River Vyrnwy.
Cain's source is just west of Llanfyllin, at the confluence of the Nant Alan and Nant Fyllon.[1]
After flowing east through Llanfyllin, where it is joined by the small River Abel, it continues eastwards alongside the A490 highway. It then turns north-east to pass through Llanfechain and is joined by the Nant Llys before finally flowing east again.[2] It is fed by the Brogan,[3] before joining the Vyrnwy near Llansantffraid-ym-Mechain.[4]
The Cain is 16 km long.[5]