| Mode: | Basketball |
| Year: | 1983–84 |
| Team: | Illinois Fighting Illini |
| Conference: | Big Ten Conference |
| Short Conf: | Big Ten |
| Coachrank: | 6 |
| Aprank: | 6 |
| Record: | 26–5 |
| Conf Record: | 15–3 |
| Head Coach: | Lou Henson |
| Asst Coach1: | Dick Nagy |
| Asst Coach2: | Jimmy Collins |
| Asst Coach3: | Bob Hull |
| Hc Year: | 9th |
| Ac1 Year: | 5th |
| Ac2 Year: | 1st |
| Ac3 Year: | 4th |
| Captain: | Quinn Richardson |
| Mvp: | Bruce Douglas |
| Mvp2: | Quinn Richardson |
| Stadium: | Assembly Hall |
| Champion: | Big Ten Conference co-champions |
| Bowl: | NCAA men's Division I tournament |
| Bowl Result: | Elite Eight |
The 1983–84 Illinois Fighting Illini men's basketball team represented the University of Illiniois.
The 1983–84 season brought Illinois its 12th Big Ten Conference championship in a season where Illinois had four overtime games including an epic four-overtime 75–66 victory over Michigan. The next game was a two-overtime win at Iowa, Lou Henson’s 400th victory as a college head coach. The Illini recorded a 26-5 mark and were 15-3 in Big Ten play, tying Purdue for the league title. This season also marked Illinois’ first back-to-back 20 win seasons since 1951–52. The Illini would go on to record a total of nine consecutive 20-win seasons from 1982–83 to 1990–91. Illinois advanced to the NCAA Regional Finals before dropping a heart-breaking 54–51 loss to Kentucky on its home court, causing the NCAA to put a rule in place not allowing a school to play in a tournament game on its home court. Rumors also were floated that the outcome was predetermined, with home team time clock operations being implicated in part.
Source[1]
|-!colspan=12 style="background:#DF4E38; color:white;"| Non-Conference regular season|-!colspan=9 style="background:#DF4E38; color:#FFFFFF;"|Big Ten regular season |-!colspan=9 style="text-align: center; background:#DF4E38"|NCAA Tournament[2] |-
| Player | Games Played | Minutes Played | Field Goals | Free Throws | Rebounds | Assists | Blocks | Steals | Points |
|---|---|---|---|---|---|---|---|---|---|
| Efrem Winters[3] | 31 | 1039 | 182 | 92 | 205 | 54 | 21 | 19 | 456 |
| Bruce Douglas[4] | 31 | 1113 | 159 | 81 | 136 | 177 | 5 | 73 | 399 |
| Doug Altenberger[5] | 31 | 1125 | 143 | 66 | 15 | 68 | 4 | 39 | 352 |
| George Montgomery[6] | 31 | 967 | 124 | 53 | 224 | 53 | 17 | 27 | 301 |
| Quinn Richardson[7] | 31 | 1029 | 94 | 50 | 61 | 93 | 0 | 23 | 238 |
| Scott Meents[8] | 28 | 465 | 61 | 23 | 91 | 33 | 25 | 9 | 145 |
| Tom Schafer | 29 | 302 | 28 | 23 | 43 | 9 | 1 | 6 | 79 |
| Tony Wysinger | 30 | 192 | 15 | 27 | 14 | 23 | 0 | 11 | 57 |
| Reggie Woodward | 14 | 43 | 12 | 4 | 10 | 5 | 0 | 3 | 28 |
| Don Klusendorf | 19 | 55 | 4 | 10 | 10 | 6 | 0 | 1 | 18 |
| Anthony Welch | 2 | 25 | 6 | 2 | 2 | 0 | 0 | 0 | 14 |
| Dee Maras | 6 | 30 | 3 | 0 | 11 | 2 | 0 | 1 | 6 |
| Drag Marinkovich | 4 | 6 | 2 | 2 | 0 | 0 | 0 | 0 | 6 |
| Joe Klauke | 2 | 2 | 1 | 0 | 0 | 0 | 0 | 0 | 2 |
| Tom Siegel | 3 | 3 | 1 | 0 | 1 | 0 | 0 | 0 | 2 |
| Stephan Freeman | 2 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
See main article: 1983–84 NCAA Division I men's basketball rankings.