Sudair or Sudayr (Arabic: سدير) is a historical region in Najd in the central of Saudi Arabia, and is located approximately 150 km north of the Saudi capital, Riyadh. The region lies in a valley directly to the east of the Tweig escarpment, which runs across Najd starting from Sudair in the north and ending near Wadi ad-Dawasir in the south.
Before the modern era, the region, like most others in Najd, depended on the valley's ability to retain rainwater, and its people mainly subsisted on the cultivation of grains and dates. The local variety of dates in Sudair is known as kudry, and is darker in color and has a stronger flavor than other varieties of dates grown in the country. Graded as low quality locally, the kudry is highly prized abroad.
A large-scale petrochemical complex is currently being constructed near Hautat Sudair. Upon completion, the project is expected to be on the magnitude of the industrial complexes of Jubail, and will serve as a bridge between the industrial zones of Jubail on the east coast and Yanbu on the west.