Tarik Benhabiles was the defending champion but lost in the second round to Thomas Muster.
Muster won in the final, 6–1, 6–7(3–7), 6–2, against Guillermo Pérez Roldán.
Seeds
Guillermo Pérez Roldán (final) Thomas Muster (champion) Goran Prpić (semifinals) Martin Střelba (first round) Paul Haarhuis (first round) Tomás Carbonell (semifinals) Mark Koevermans (quarterfinals) Franco Davín (second round)
Draw
Finals
Top half
Bottom half
External links 1990 Casablanca Open draw