Queues were stretching back as far as Gillingham following a crash on the M2 near Sittingbourne.
The accident happened at about 4pm on the coast-bound carriageway when two cars and a people carrier collided.
The crash blocked one lane of the motorway, but the other lane remains open.
Police and traffic officers were called to the scene.
There are not thought to have been any serious injuries and the road was clear by 6pm.