The A299 is closed in both directions between A253 (Monkton Roundabout) and A28 Canterbury Road (St Nicholas at Wade Roundabout) due to a serious accident.
Police, fire and ambulance services are at the scene. Motorists report they are now being turned back from the area.
A Kent Police spokesperson said: “Kent Police was called to a report of a collision involving a motorbike on the A299 near Monkton at 4.15pm.
“Officers are currently at the scene and the A299 is closed in both directions between the roundabout near St Nicholas-at-Wade and the roundabout near Monkton.”