The 2008 NCAA Tournament is the only year when all four No. 1 seeds advanced to the Final Four.
Those No. 1 seeds were North Carolina, UCLA, Memphis, and Kansas. The Jayhawks beat Memphis in overtime during the championship game, 75-68.
It's common for the national champion to be a high seed; seven of the last 10 national championships have been seeded No. 1 in one of the four regions.
However, as any seasoned March Madness bracketologist can tell you, it's not all that common for every No. 1 seed to advance, which is why it's often wise to forecast a few reasonable upsets when the NCAA Tournament comes around each year.