Patrik Kühnen and Tore Meinecke were the defending champions but they competed with different partners that year, Kühnen with Udo Riglewski and Meinecke with Ricki Osterthun.
Guy Forget and Henri Leconte were the defending champions but only Leconte competed that year with Eric Winogradsky.
The 1991 German Open was a tennis tournament played on outdoor clay courts and was part of the ATP Super 9 of the 1991 ATP Tour. It took place at the Rothenbaum Tennis Center in Hamburg, Germany, from May 6 through May 13, 1991. Sergio Casal and Emilio Sánchez won in the final against Cássio Motta and Danie Visser, 7–6, 7–6.
Paul Annacone and Christo van Rensburg were the defending champions. Annacone competed alongside Kelly Evernden but lost in the semifinals, while van Rensburg played with Kevin Curren and lost in the quarterfinals.
Darren Cahill and Mark Kratzmann won the title, defeating Udo Riglewski and Michael Stich 7–5, 6–2, in the final.
John Fitzgerald and Anders Järryd defeated Javier Frana and Leonardo Lavalle in the final, 6–3, 6–4, 6–7(7–9), 6–1 to win the gentlemen's doubles title at the 1991 Wimbledon Championships. It was Fitzgerald and Järryd's third Wimbledon final in four years.
Boris Becker and Michael Stich were the defending champions, but Becker did not compete this year. Stich teamed up with Udo Riglewski and lost in quarterfinals to Sergio Casal and Emilio Sánchez.
Rick Leach and Tim Pawsat were the defending champions, but none competed this year.
Horacio de la Peña and Diego Nargiso were the defending champions, but Nargiso did not compete this year. De la Peña teamed up with Boris Becker and lost in the first round to Marcos Górriz and Jan Gunnarsson.
Patrick Baur and Udo Riglewski were the defending champions, but none competed this year.
Paul Haarhuis and Jacco Eltingh were the defending champions, but lost in the quarterfinals to Diego Nargiso and Udo Riglewski.
Pieter Aldrich and Danie Visser were the defending champions, but Aldrich did not compete this year. Visser teamed up with Neil Broad and lost in semifinals to Jan Siemerink and Daniel Vacek.
Jakob Hlasek and Tomáš Šmíd were the defending champions but Hlasek did not compete this year, as he decided to focus on the singles tournament. Šmíd teamed up with Jan Gunnarsson and lost in the first round to tournament runners-up Omar Camporese and Claudio Mezzadri.
David Adams and Andrei Olhovskiy were the defending champions, but lost in the first round to Yevgeny Kafelnikov and Menno Oosting.
Shelby Cannon and Scott Melville were the defending champions, but they lost in the second round to Ronald Agénor and Younes El Aynaoui.
Juan Garat and Roberto Saad were the defending champions, but Garat did not compete this year. Saad teamed up with Patricio Arnold and lost in the quarterfinals to David Adams and Andrei Olhovskiy.
Todd Woodbridge and Mark Woodforde were the defending champions, but decided to compete at Indian Wells in the same week.
Sergio Casal and Emilio Sánchez were the defending champions, but lost to Omar Camporese and Goran Ivanisevic in the quarterfinals. Camporese and Ivanisevic went on to win the title, defeating Luke Jensen and Laurie Warder in the finals, 6–2, 6–3.
Emilio Sánchez was the defending champion, but lost in the semifinal to Horacio de la Peña.
Glenn Layendecker and Byron Talbot were the defending champions, but none competed this year. Layendecker retired from professional tennis at the end of the 1992 season, while Talbot opted to compete at Washington, D.C. during the same week.
Pieter Aldrich and Danie Visser were the defending champions, but Aldrich did not compete this year. Visser teamed up with Gary Muller and lost in the quarterfinals to Nick Brown and Richard Vogel.
Alberto Mancini 
Yannick Noah 
Marcelo Filippini 
Horst Skoff 
