Saudi Arabia's state news agency says King Abdullah has undergone successful back surgery.
The agency said in a statement that "the surgery, thanks be to God, was successful." No further details were immediately available.
The king was admitted to hospital in Riyadh early on October 16.
The ruler of the conservative Islamic kingdom, who is thought to be in his mid-80s, suffered a herniated disc late last year that required two operations in the United States.
King Abbullah's health has raised questions over who will succeed him.
His heir is Crown Prince Sultan.
compiled from agency reports