See main article: 1990 Mercedes Cup.
Martín Jaite was the defending champion, but lost in the second round to Karel Nováček.
Goran Ivanišević won the title by defeating Guillermo Pérez Roldán 6–7(2–7), 6–1, 6–4, 7–6(7–5) in the final.[1] [2]
All seeds received a bye into the second round.