Has a No. 16 seed ever beaten a No. 1 seed at the NCAA men's basketball tournament? The short answer is no.
Though it has happened in the women's tournament, there hasn't been that big of an upset on the men's side, though there have been some close calls.
There have been eight No. 2 seeds that have been beaten by No. 15 seeds, most recently Middle Tennessee knocking off Michigan State in 2016 and Florida Gulf Coast's "Dunk City" crew over Georgetown in 2013.
The first year of the 64–team tournament (now 68 teams) was in 1985. Of the 128 such games between a No. 1 seed against a No. 16 seed, the top seed has won by an average of nearly 25 points.
The last time a 1–16 matchup was decided by less than 10 points came in Arizona’s 68-59 victory over Weber State in 2014.
Some of the closer games both happened in 1989. Georgetown was the top seed in the East Region and survived a 50–49 squeaker against Princeton. The Hoyas lost to Duke in the Regional Final.
The Southeast Region's top seed was Oklahoma, who rallied from a 17-point first half deficit against East Tennessee State before prevailing 72–71. The Sooners were eventually beaten by Virginia in the Sweet 16.
In 1990, top seed Michigan State was taken to overtime by Murray State. The Spartans lost a controversial game to Georgia Tech in the Southeast Region's Sweet 16.