1991 OTB International Open – Men's singles

Ramesh Krishnan was the defending champion, but lost in the first round this year.

Michael Stich won the tournament, beating Emilio Sánchez in the final, 6–2, 6–4.

Seeds
• # 🇩🇪 Michael Stich (champion)

• # 🇪🇸 Sergi Bruguera (quarterfinals)

• # 🇪🇸 Emilio Sánchez (final)

• # Andrei Cherkasov (quarterfinals)

• # Alexander Volkov (quarterfinals)

• # 🇦🇹 Horst Skoff (semifinals)

• # 🇦🇺 Todd Woodbridge (quarterfinals)

• # 🇪🇸 Francisco Clavet (semifinals)