The 2006 NCAA Division I men's basketball tournament involved 65 teams playing in a single-elimination tournament to determine the national champion of men's NCAA Division I college basketball as a culmination of the 2005–06 basketball season. It began on March 14, 2006, and concluded with the championship game on April 3 at the RCA Dome in Indianapolis, Indiana. The Final Four featured no top seeds for the first time since the tournament expanded to 64 teams in 1985 (the first time since 1980), with the highest remaining seed being Oakland region winner, #2 UCLA, making their first Final Four appearance since their 1995 national championship. For only the second time in history, an 11-seed advanced to the Final Four as George Mason of the Colonial Athletic Association (CAA) won the Washington, D.C. region. Those two teams were joined by Atlanta region winner LSU (who was the first team to advance to the Final Four as an 11-seed in 1986), and Minneapolis region winner Florida, who had not made the Final Four since their runner-up finish in 2000 also in Indianapolis. Florida won its first-ever national basketball championship by defeating UCLA 73–57 in the final game. Florida's Joakim Noah was named the Most Outstanding Player of the NCAA tournament. George Mason's run was one of several upsets by lower-seeded teams in the tournament. For the second consecutive year, a No. 14 seed beat a No. 3 seed as Northwestern State defeated Iowa. No. 13 seed Bradley also defeated No. 4 seed Kansas and advanced to the Sweet Sixteen by defeating No. 5-seeded Pittsburgh in the second round. Two No. 12 seeds won as well, as Montana and Texas A&M both won their respective First round matchups. For the second straight year, Milwaukee won as a double-digit seed, this time as the No. 11-seeded Panthers defeated Oklahoma in the first round. American East Conference champion Albany and ASUN champion Belmont made their first appearance in the tournament.

Tournament procedure

A total of 65 teams were selected to participate in the tournament. Of that total, 31 of the teams earned automatic bids by winning their conference tournaments. Penn earned an automatic bid by winning the regular-season title of the Ivy League, which did not conduct a conference tournament. The remaining 34 teams were granted "at-large" bids, which are extended by the NCAA Selection Committee. The initial game on March 14 officially named the opening round game, but popularly called the "play-in game", had Monmouth, winner of the Northeast Conference tournament, facing Hampton, who won the Mid-Eastern Athletic Conference tournament, for a chance to play top seed Villanova in the first round of the Tournament. Monmouth defeated Hampton, 71–49, to advance to play Villanova. All teams were seeded from 1 to 16 within their regions. The Selection Committee seeded the entire field from 1 to 65. In a practice used since 2004, the ranking of the four top seeds against each other would determine the pairings in the Final Four. The top overall seed would be seeded to play the fourth overall seed in the national semifinals, should both teams advance that far. In 2006, these rankings were as follows: No. 1 Duke, No. 2 Connecticut, No. 3 Villanova, and No. 4 Memphis.

Schedule and venues

The following are the sites that were selected to host each round of the 2006 tournament: Opening Round First and Second Rounds Regional semifinals and finals (Sweet Sixteen and Elite Eight) National semifinals and championship (Final Four and championship)

Qualifying teams

Automatic bids

The following teams were automatic qualifiers for the 2006 NCAA field by virtue of winning their conference's tournament (except for the Ivy League, whose regular-season champion received the automatic bid).

Listed by region and seeding

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Bids by conference

Bracket

Opening Round game – Dayton, Ohio

Winner advances to Minneapolis Regional vs. No. 1 Villanova.

Atlanta Regional

Oakland Regional

Minneapolis Regional

Washington, D.C. Regional

Final Four – Indianapolis, Indiana

Record by conference

• Monmouth University won the Opening Round game. The America East, Atlantic Sun, Big South, Big West, Ivy, MAAC, MAC, MEAC, Ohio Valley, SoCon, SWAC, Mid-Continent, and Sun Belt conferences all went 0–1. The columns R32, S16, E8, F4, and CG respectively stand for the Round of 32, Sweet Sixteen, Elite Eight, Final Four, and championship Game.

Announcers

Greg Gumbel once again served as the studio host, joined by analysts Clark Kellogg and Seth Davis.