| Champ: | Ivan Lendl |
| Runner: |  Stefan Edberg |
| Score: | 4–6, 7–6(7–3), 5–2 retired |
| Draw: | 128 |
| Seeds: | 16 |
See main article: 1990 Australian Open.
Defending champion Ivan Lendl defeated Stefan Edberg in the final, 4–6, 7–6(7–3), 5–2 ret., to win the men's singles tennis title at the 1990 Australian Open. It was his second Australian Open title and eighth and last major singles title overall. Edberg was forced to retire during the third set of the final due to a torn stomach muscle. This marked the first occasion since the 1911 Wimbledon Championships that a man withdrew during the championship match of a singles major.[1]
Former world No. 1 John McEnroe created controversy after he was disqualified from his fourth round match for unsportsmanlike conduct. He received a warning for intimidating a linesperson, a point penalty after smashing his racket, and was defaulted for arguing with and abusing the umpire, supervisor and tournament referee.
See also: 1 and 1. Ivan Lendl (champion)
See also: 2 and 8. Boris Becker (quarterfinals)
See also: 3 and 6. Stefan Edberg (final, retired because of a torn stomach muscle injury)
See also: 4 and 3. 
John McEnroe (fourth round, defaulted for unsportsmanlike conduct)
See also: 5 and 5. Aaron Krickstein (fourth round)
See also: 6 and 4. Tim Mayotte (first round)
See also: 7 and 2. 
Emilio Sánchez (first round)
See also: 8 and 7. Mats Wilander (semifinals)
See also: 9 and 2. 
Andrés Gómez (fourth round)
See also: 10 and 7. Carl-Uwe Steeb (first round)
See also: 11 and 5. Andrei Chesnokov (second round)
See also: 12 and 4. 
Yannick Noah (semifinals)
See also: 13 and 3. Sergi Bruguera (second round)
See also: 14 and 6. Jim Courier (second round)
See also: 15 and 1. 
Thomas Muster (third round)
See also: 16 and 8. Miloslav Mečíř (fourth round)
See main article: 1990 Australian Open – Men's singles qualifying.
a. No. 1 seed Ivan Lendl won the final after No. 3 seed Stefan Edberg was forced to retire in the third set with a torn stomach muscle injury.[1]
b. Mikael Pernfors advanced to the quarterfinals after No. 4 John McEnroe was defaulted in the fourth set by chair umpire Gerry Armstrong for unsportsmanlike conduct.[2]
c. David Wheaton advanced to the fourth round after Mark Woodforde was forced to retire in the second set with a right ankle injury.[3]