A truck and trailer unit carrying offal has tipped over on State Highway 2 at Kotemaori, west of Wairoa, blocking the road.
The road will be closed for about three hours so heavy lifting equipment can be brought in to remove the truck, police said.
No detours are available, but emergency services will try to direct traffic through the road where possible.
Police advised motorists to avoid the area and be patient.
No one was injured in the crash.