Saudi Arabia's crown prince begins a three-day visit to neighbouring Qatar on Monday, the latest sign of a thaw in bilateral relations.
Saudi Arabia's present king made an official visit to Qatar in 2000
The Saudis recalled their ambassador from Qatar in 2002, in protest at coverage by the Qatari-owned satellite television channel, al-Jazeera.
in 2007 Saudi King Abdullah attended a summit in Qatar and Qatar's emir, Sheikh Hamad, has visited Saudi Arabia.
Saudi Arabia finally re-established full diplomatic ties on Sunday.
Some observers say al-Jazeera has toned down criticism of Saudi Arabia over the past year as a prelude to the rapprochement.
The last straw in 2002 was one of the channel's infamous studio debates in which participants launched blistering verbal attacks on Saudi Arabia's rulers.
Saudi Arabia is the Gulf's most conservative Arab state, while Qatar has tried to forge an independent stance, including on media freedom and contacts with Israel.