Paul Haarhuis and Yevgeny Kafelnikov were defending champions, but they lost in the final to third seeds Bob and Mike Bryan, who won the first Grand Slam title of their careers.
Mark Knowles and Daniel Nestor were the defending champions, but lost in the final to Michaël Llodra and Fabrice Santoro.
Todd Woodbridge and Mark Woodforde were the defending champions but only Woodbridge competed that year with Wayne Arthurs.
Jiří Novák and David Rikl were the defending champions but lost in the second round to Tomás Carbonell and Nicolás Lapentti.
Pablo Albano and Cyril Suk were the defending champions but they competed with different partners that year, Albano with Lucas Arnold and Suk with Marius Barnard.
Lleyton Hewitt and Sandon Stolle were the defending champions but only Stolle competed that year with Max Mirnyi.
Jonathan Stark and Kevin Ullyett were the defending champions and won in the final 6–1, 6–4 against Leoš Friedl and Radek Štěpánek.
Defending champions Cyril Suk and Helena Suková defeated Andrei Olhovskiy and Larisa Neiland in the final, 4–6, 6–3, 6–4 to win the mixed doubles tennis title at the 1997 Wimbledon Championships.
Mark Knowles and Daniel Nestor were the defending champions but lost in the second round to Joshua Eagle and Andrew Florent.
Pablo Albano and Àlex Corretja were the defending champions, but Corretja did not participate this year. Albano partnered Jonas Björkman, losing in the semifinals.
Marc-Kevin Goellner and Richey Reneberg were the defending champions, but did not participate together this year. Goellner partnered Wayne Ferreira, losing in the quarterfinals. Reneberg partnered Jonathan Stark, losing in the semifinals.
Mahesh Bhupathi and Max Mirnyi were the defending champions, but lost in the quarterfinals to Michaël Llodra and Fabrice Santoro.
The 1998 Mercedes Cup was a men's tennis tournament played on Clay in Stuttgart, Germany, that was part of the International Series Gold of the 1998 ATP Tour. It was the fiftieth edition of the tournament and was held 20 July – 26 July.
The 1998 Generali Open was a men's tennis tournament played on Clay in Kitzbühel, Austria that was part of the International Series of the 1998 ATP Tour. It was the forty-third edition of the tournament and was held from 27 July – 2 August 1998.
Justin Gimelstob and Sébastien Lareau were the defending champions, but none competed this year.
Lucas Arnold Ker and Martín García were the defending champions, but competed this year with different partners. Arnold Ker teamed up with Pablo Albano and lost in quarterfinals to Devin Bowen and Mariano Hood, while García teamed up with Tomás Carbonell and lost in semifinals to Alberto Martín and Eyal Ran.
Olivier Delaître and Fabrice Santoro were the defending champions, but both players decided to rest after competing in the quarterfinals of the Davis Cup. However, Santoro competed in the singles tournament, losing in first round to Jiří Novák.
Gustavo Kuerten and Fernando Meligeni were the defending champions, but Meligeni did not compete this year. Kuerten teamed up with Jaime Oncins and lost in quarterfinals to tournament runners-up Aleksandar Kitinov and Eric Taino.
Tom Kempers and Daniel Orsanic were the defending champions, but Kempers did not compete this year. Orsanic teamed up with Tomás Carbonell and lost in the second round to Jürgen Melzer and Alexander Peya.
Mariano Hood and Sebastián Prieto were the defending champions, but lost in the quarterfinals to Devin Bowen and Alberto Martín.
Pablo Albano 
Cyril Suk 
Joshua Eagle 
