1991 Australian Men's Hardcourt Championships – Singles

Thomas Muster was the defending champion of the singles event at the Australian Men's Hardcourt Championships tennis tournament, but did not participate this year.

Nicklas Kulti defeated Michael Stich 6–3, 1–6, 6–2 to secure the title.

Seeds

 * 1) 🇩🇪 Boris Becker (first round)
 * 2) 🇺🇸 Jim Courier (semifinals)
 * 3) 🇦🇹 Horst Skoff (first round)
 * 4) 🇪🇸 Sergi Bruguera (first round)
 * 5) 🇸🇪 Magnus Gustafsson (second round)
 * 6) 🇩🇪 Michael Stich (final)
 * 7)  Mark Koevermans (first round)
 * 8) 🇦🇺 Todd Woodbridge (second round)