| River Cegidog | |
| Name Etymology: | From Welsh cegidog, "abounding with hemlock" (cegid), "hemlock place" |
| Subdivision Type1: | Country |
| Subdivision Name1: | Wales |
| Subdivision Type3: | Counties |
| Source1 Location: | near Rhydtalog, Flintshire |
| Source1 Coordinates: | 53.0759°N -3.1478°W |
| Source1 Elevation: | 320m (1,050feet) |
| Mouth: | confluence with River Alyn |
| Mouth Location: | Sydallt, Wrexham County Borough |
| Mouth Coordinates: | 53.0932°N -3.0273°W |
| Mouth Elevation: | 60m (200feet) |
The River Cegidog is a river in north-east Wales. It flows mainly through Flintshire but towards the end of its course it forms the border between Flintshire and Wrexham County Borough.
Its source lies in the hills of southernmost Flintshire to the east of Rhydtalog village. It flows in a roughly north-easterly direction before turning south-east through the villages of Llanfynydd and Ffrith where the Nant-y-Ffrith stream flows into it. It then heads north-east again through a wooded valley before joining the River Alyn at Cefn-y-bedd.
The name of the river indicates a place where hemlock grows.[1]