Gates, who will hold talks with King Abdullah bin Abdul Aziz, said: "I think we can always use Saudi co-operation on these issues in the Gulf region."
Abdullah and Crown Prince Sultan bin Abdul Aziz, the Saudi defence minister, received Gates on Wednesday at a desert camp at Rawdhat Khuraim.
"Prince Meqrin bin Abdul Aziz, the head of Saudi's intelligence services, was also present, the Saudi press agency reported.
Patriot deployment
The visit comes against the backdrop of the US president's decision to deploy a Patriot missile defence battalion to the region. The Bush administration says it is intended as protection against any possible Iranian ballistic missile threat.
The move was announced last week as part of the US strategy for the region, which includes the deployment of an additional 21,500 troops to Iraq.
Gates flew to Saudi Arabia from Afghanistan, where he said that US commanders had also asked for more troops.
Donald Rumsfeld, Gates predecessor as US defence secretary, visited Saudi Arabia in April 2003.