Usk was an ancient hundred of Monmouthshire.
It was situated in the centre of the county, bounded to the north by the hundreds of Abergavenny and Raglan; to the east and south by the hundred of Caldicot; and to the west by the hundred of Wentloog.
It contains the following ancient parishes:
- Caerleon township
- Gwehelog Fawr
- Gwernesney
- Kemeys
- Kemeys Commander
- Llanbadog
- Llandegveth
- Llangattock
- Llangeview
- Llangwm
- Llangybi Fawr
- Llanhennock
- Llanllywel
- Llanthewy Vach
- Llantrissant Fawr
- Llanvihangel Pont y Moile
- Llanfrechfa
- Panteg
- Tintern
- Tredunnock
- Trostre
- Usk
The administration of the area is now divided between the local authorities of Newport, Torfaen and Monmouthshire.