The 1989 Mercedes Cup, was a men's tennis tournament played on outdoor clay courts and held at the Tennis Club Weissenhof in Stuttgart, West Germany that was part of the 1989 Grand Prix circuit. It was the 12th edition of the tournament was held from 24 July until 30 July 1989. Fourteenth-seeded Martín Jaite won the singles title.
See main article: 1989 Mercedes Cup – Singles. 
Martín Jaite defeated Goran Prpić, 6–3, 6–2
See main article: 1989 Mercedes Cup – Doubles. Petr Korda / Tomáš Šmíd defeated 
Florin Segărceanu / Cyril Suk, 6–3, 6–4