The Newell Highway is closed in both directions in The Pilliga due to a B-Double crash near Brandons Road, about 45 kilometres south of Narrabri.
Motorists are advised to avoid the area and consider using Kamilaroi and Oxley Highways instead.
Motorists should also allow plenty of extra travel time.
Emergency services are on site.
For the latest traffic information, download the Live Traffic NSW app, visit www.livetraffic.com or call 132 701.