A Welsh Ambulance Service spokeswoman said they took a woman in her fifties to Nevill Hall Hospital in Abergavenny.
She said they were called at 2.23pm today and a paramedic in a rapid response car and an emergency ambulance responded.
Firecrews have left the crash scene on the A449.
One lane is closed on the A449 southbound as a result of the crash.
FIREFIGHTERS are en-route to a crash on the A449 southbound between Raglan to Usk this afternoon.
The crash is reported to be between a lorry and a car towing a caravan.
Drivers are advised to avoid the area if possible as delays are expected.