Hoosier hysteria is the excitement surrounding basketball in the U.S. state of Indiana. This excitement generally revolves around the Indiana High School Boys Basketball Tournament, the Indiana Hoosiers men's basketball team of Indiana University (IU), the Purdue Boilermakers men's basketball team of Purdue University, the Butler Bulldogs men's basketball team of Butler University, the Indiana Pacers of the National Basketball Association (NBA) and the Indiana Fever of the Women's National Basketball Association (WNBA).

Indiana's passion for basketball was observed and written about by basketball's inventor, James Naismith. In 1925, Naismith visited an Indiana basketball state finals game along with 15,000 screaming fans. He later wrote that while it was invented in Massachusetts, "basketball really had its origin in Indiana, which remains the center of the sport". In the 1954 Indiana High School Boys Basketball Tournament, underdog Milan, with just an enrollment size of 161 students, defeated the heavily favored Muncie Central to win the state title. The 1986 David Anspaugh film Hoosiers, starring Gene Hackman, is loosely based on the 1954 tournament.

Since the late 20th century, numerous basketball stars have generated excitement and fan generation in Indiana. One of these players, Larry Bird, became one of the most marketed and popular Indiana athletes in history due to his play for the Indiana State Sycamores from 1976 to 1979, and for his head coaching tenure for the Indiana Pacers from 1997 to 2000. Players such as Reggie Miller and Jalen Rose became popular during Bird's tenure as head coach of the Pacers. In the 21st century, athletes such as Caitlin Clark, Paul George and Tyrese Haliburton have generated similar excitement to a lesser degree. The Caitlin Clark effect has particularly generated excitement around the Indiana Fever of the WNBA.

High school basketball Through the 2009-2010 NBA season, 152 Hoosier athletes have played professional basketball in the world's top league. Considering the size of the state (population 6.4 million), this makes Indiana high schools by far the most successful at developing NBA players per capita. Today there are 22 Hoosiers in the NBA - more than one for every 150,000 male residents. In 2017, Indiana natives won the NBA and D-league Slam Dunk Contests, NBA and D-league 3-point contests, and won runner-up in the NBA Skills Challenge.

Historically, each of the several hundred small towns of Indiana had its own small school system. Before consolidation of many of these rural school districts in the last half of the twentieth century, Indiana high schools had fewer students than those of most other states; basketball was a natural game for these schools since it only required five starters and a few reserves and even a few great players could make a strong team.

The Franklin Wonder Five, led by Fuzzy Vandivier, was the first team to win the state championship in three consecutive years, from 1920 to 1922. This accomplishment would not be matched for over six decades.

After Milan's Miracle in the 1950s, no school with an enrollment of less than 500 won another boys' State title under the all-comers format. As school consolidation became more common and as more rural residents migrated to cities making large high schools grow even larger, smaller high schools had only a mismatch to look forward to come tournament time, as success concentrated in Indiana's large urban and suburban schools. Starting with the 1997–1998 season, Indiana established a controversial four-class system for its basketball championship, although many other sports remain single-class. The state's move to this new system has, to some extent, diminished the phenomenon and public opinion is widely split on the merits of "class basketball."

Aside from the "Milan Miracle," the story of Crispus Attucks High School ranks as one of the greatest in Indiana high school basketball tradition. In 1955, the year after Attucks had lost in the semistate final (state quarterfinals) to Milan's championship team, Attucks gained fame by winning the Indiana state championship, becoming the first all-black school in the nation to win a state title open to all schools regardless of race. Crispus Attucks repeated as champions in 1956, becoming the first Indiana high school team to complete a season undefeated. The Attucks teams of 1954 through 1956 were led by Oscar Robertson. Milan and Crispus Attucks are memorialized for their accomplishments and tradition at the Indiana State Museum as well as at the Indiana Basketball Hall of Fame in New Castle.

A highlight of the single-class tournament was the 1990 State Championship game, in which the paid attendance was over 40,000 fans. This turnout of fans who witnessed Damon Bailey's Bedford-North Lawrence Stars win the State Championship stands as the largest crowd ever to witness a high school basketball game.

After the 1997 season (when Bloomington North won the final single-class State Championship), the IHSAA controversially did away with the single-class system, ending the run of single-class champions in Indiana. Some argue Hoosier Hysteria was diminished as a result. In 2003, DeKalb High School (1200 students) nearly defeated Pike High School (3000 students). The Indiana tournament is still the most attended in the nation, with final four games for the two larger divisions regularly selling out Gainbridge Fieldhouse (formerly Conseco Fieldhouse and Bankers Life Fieldhouse).

High school gymnasiums

Indiana also possesses a disproportionate share of the country's largest high school basketball gymnasiums, including nine of the ten largest high school gyms in the country and eighteen of the top twenty. Seventeen venues in Indiana today have a capacity of over 6,000, the largest being the New Castle Fieldhouse, seating 9,325.

College basketball Hoosier hysteria extends to college basketball. In NCAA Division I basketball, Indiana's colleges and universities have a long history. Big Ten rivals Purdue University and Indiana University and the University of Notre Dame are the most notable, with national and conference championships. Smaller schools such as Indiana State University, Ball State University, Butler University, the University of Evansville, IU Indy, Purdue Fort Wayne, the University of Southern Indiana, and Valparaiso University add to the mix. Vincennes University have a tradition in the junior college ranks, and in Division II St. Joseph's and the University of Indianapolis have added their own successes to Indiana basketball. Wabash College won the Men's Division III NCAA Championship in 1982 and their 1905 24–0 team was considered World Champions; DePauw University and Manchester College were Division III National Finalists.

+Teams with national championshipsTeamChampionshipYears wonIndianaNCAA Division I Men's Tournament1940, 1953, 1976, 1981, 1987Notre DameNCAA Division I Women's Tournament2001, 2018PurdueNCAA Division I Women's Tournament1999EvansvilleNCAA Division II Men's Tournament1959, 1960, 1964, 1965, 1971Southern IndianaNCAA Division II Men's Tournament1995WabashNCAA Division III Men's Tournament1982TrineNCAA Division III Men's Tournament2024DePauwNCAA Division III Women's Tournament2007, 2013Indiana StateNAIA Men's Tournament1950VincennesNJCAA Division I Men's Tournament1965, 1970, 1972, 2019Oakland CityNCCAA Division I Men's Tournament1999BethelNCCAA Division I Men's Tournament1992, 1993, 2000, 2007, 2023NCCAA Division I Women's Tournament2000, 2003, 2004, 2006, 2010, 2011Indiana WesleyanNCCAA Division I Men's Tournament1995, 2008NCCAA Division I Women's Tournament2002GraceNCCAA Division I Women's Tournament2024HuntingtonNCCAA Division I Women's Tournament1984, 1991, 1992

Ball State Cardinals

The Ball State Cardinals have won several conference championships and earned a number of NCAA Tournament berths over the years, including: Seven Mid-American Conference Season Championships Seven Mid-American Conference (MAC) Tournament Championships (and subsequent NCAA Tournament appearances) Bonzi Wells, a Muncie, Indiana native, was a four-year letterwinner at Ball State, finishing his career as the Mid-American Conference's all-time leading scorer, and leading the NCAA in steals. Ball State's highest finish in the NCAA Tournament came in 1990, when they defeated Gary Payton's Oregon State Beavers and Coach Denny Crum's Louisville Cardinals before falling to eventual champion UNLV by 2, 69–67.

Butler Bulldogs

Home of the legendary Hinkle Fieldhouse, the largest basketball arena in the world from 1928 to 1950 (including professional arenas). Hinkle hosted the Indiana High School Athletic Association Championships for many years (including Milan's 1954 championship), Butler University also is notable for its men's and women's basketball teams. The Bulldogs advanced to the Sweet 16 of the NCAA Tournament in the 2003 and 2007 seasons. In 2006, the Bulldogs won the 2006 Preseason NIT, beating most notably Indiana and Notre Dame to reach the semifinals in New York City. Behind a strong performance from guard A.J. Graves, the Bulldogs defeated Tennessee and Gonzaga at Madison Square Garden. In 2010, Butler reached their first Final Four as a #5 seed, beating #12 seeded UTEP in the first round behind a flurry of 3-pointers, edging out a very good #13 seed Murray State (who upset #4 seed Vanderbilt in the first round), and then in the Sweet 16, Butler upset #1 seed Syracuse, and in a thrilling Elite Eight game Butler upset #2 seed Kansas State. The Bulldogs made it to the Finals of the NCAA Tournament after defeating #5 seed Michigan State from the Midwest division. The Bulldogs played against #1 seeded Duke from the South in the finals but lost in a close game, with a potential game-winning shot by Gordon Hayward from just inside half-court rimming out. In 2011, Butler returned to the NCAA title game for a second straight year. However, Butler lost 53–41 to Connecticut, shooting a historically low 18.8 percent from the field — the worst in any NCAA title game and the worst in any NCAA tourney game since Harvard against Ohio State in 1946.

Evansville Purple Aces

The Evansville Purple Aces have won five national championships in the NCAA College Division (now known as Division II): 1959, 1960, 1964, 1965 (29–0 record), and 1971. This ranks second all-time. After joining the NCAA's Division I in 1977, Evansville was a charter member of the Midwest Collegiate Conference, now known as the Horizon League. The Aces won or shared the MCC regular season title in 1982, 1987, 1989, 1992, and 1993. They also won the conference tournament title in 1982, 1992, and 1993. The Aces are now a member of the Missouri Valley Conference, and won the 1999 regular season title. Legendary Aces coach Arad McCutchan was the first NCAA College Division coach selected to the Naismith Basketball Hall of Fame.

Franklin College Grizzlies

Franklin College (total enrollment of around 350 students), known as the "Franklin Wonder Five", declared national college champions in 1922–1923 season, staying undefeated against teams from major universities, including Notre Dame, Illinois, Purdue, and Wisconsin. Had a string of 50 consecutive victories over a 2-season span that ended in February 1924, after the team suffered its first defeat by Butler University. In 1924, turned down an offer to play the Original Celtics, the top professional team in the nation, for a claim to the "undisputed national championship". Two Indiana State Collegiate Championships (1923, 1924).

Indiana Hoosiers

Indiana's collegiate basketball squad, the Indiana Hoosiers men's basketball team has several championships to their credit:

Five NCAA National Championships (1940, 1953, 1976, 1981, 1987), placing them in a tie for fifth most all-time