| Singles | |
|---|---|
| 1990 CA-TennisTrophy | |
| Champion |  Anders Järryd |
| Runner-up |  Horst Skoff |
| Final score | 6–3, 6–3, 6–1 |
| Draw | 32 |
| Seeds | 8 |
Paul Annacone was the defending champion but lost in the second round to Thomas Muster.
Anders Järryd won in the final 6–3, 6–3, 6–1 against Horst Skoff.
Thomas Muster (semifinals)
John McEnroe (quarterfinals)
Martín Jaite (quarterfinals) Horst Skoff (final)
Carl-Uwe Steeb (second round)
Alexander Volkov (semifinals) Jimmy Arias (second round) Michael Stich (first round)| Semifinals | Final | ||||||||||||||
| 1 | Thomas Muster | 2 | 6 | ||||||||||||
| 4 | Horst Skoff | 6 | 7 | ||||||||||||
| 4 | Horst Skoff | 3 | 3 | 1 | |||||||||||
| Anders Järryd | 6 | 6 | 6 | ||||||||||||
| 6 | Alexander Volkov | 2 | 5 | ||||||||||||
| Anders Järryd | 6 | 7 | |||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | T Muster | 7 | 6 | ||||||||||||||||||||||||
 M Střelba | 6 | 4 | 1 | T Muster | 3 | 7 | 7 | ||||||||||||||||||||
| P Annacone | 7 | 7 | P Annacone | 6 | 6 | 6 | |||||||||||||||||||||
| J Tarango | 5 | 6 | 1 | T Muster | 0 | 6 | 7 | ||||||||||||||||||||
| Q | A Olhovskiy | 6 | 6 | Q | A Olhovskiy | 6 | 4 | 6 | |||||||||||||||||||
 O Delaître | 0 | 3 | Q | A Olhovskiy | 7 | 6 | |||||||||||||||||||||
 J Bates | 5 | 4 | 7 | J Arias | 5 | 4 | |||||||||||||||||||||
| 7 | J Arias | 7 | 6 | 1 | T Muster | 2 | 6 | ||||||||||||||||||||
| 4 | H Skoff | 3 | 7 | 6 | 4 | H Skoff | 6 | 7 | |||||||||||||||||||
| A Antonitsch | 6 | 5 | 2 | 4 | H Skoff | 6 | 6 | 6 | |||||||||||||||||||
| WC | R Wawra | 2 | 4 | Q |  D Poliakov | 7 | 4 | 2 | |||||||||||||||||||
| Q | D Poliakov | 6 | 6 | 4 | H Skoff | 6 | 6 | ||||||||||||||||||||
| M Sinner | 2 | 6 | L Jonsson | 4 | 3 | ||||||||||||||||||||||
| L Jonsson | 6 | 7 | L Jonsson | 6 | 6 | ||||||||||||||||||||||
| R Azar | 3 | 3 | WC/5 | C-U Steeb | 3 | 3 | |||||||||||||||||||||
| WC/5 | C-U Steeb | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 6 | A Volkov | 7 | 6 | ||||||||||||||||||||||||
| T Högstedt | 6 | 4 | 6 | A Volkov | 7 | 6 | |||||||||||||||||||||
| J Wöhrmann | 7 | 6 | J Wöhrmann | 5 | 3 | ||||||||||||||||||||||
| Q | H Mair | 5 | 1 | 6 | A Volkov | 6 | 6 | ||||||||||||||||||||
| Q |  J Siemerink | 4 | 7 | 6 | 3 | M Jaite | 2 | 1 | |||||||||||||||||||
| WC | P McEnroe | 6 | 5 | 3 | Q | J Siemerink | 3 | 3 | |||||||||||||||||||
 T Carbonell | 6 | 4 | 3 | M Jaite | 6 | 6 | |||||||||||||||||||||
| 3 | M Jaite | 7 | 6 | 6 | A Volkov | 2 | 5 | ||||||||||||||||||||
| 8 | M Stich | 5 | 2 | A Järryd | 6 | 7 | |||||||||||||||||||||
| A Järryd | 7 | 6 | A Järryd | 6 | 6 | ||||||||||||||||||||||
 J Cunha Silva | 6 | 3 | P Kühnen | 3 | 4 | ||||||||||||||||||||||
| P Kühnen | 7 | 6 | A Järryd | 7 | 6 | ||||||||||||||||||||||
| J Gunnarsson | 6 | 6 | 6 | 2 | J McEnroe | 6 | 2 | ||||||||||||||||||||
| U Riglewski | 7 | 3 | 7 | U Riglewski | 7 | 4 | 3 | ||||||||||||||||||||
| B Garrow | 6 | 6 | 4 | 2 | P McEnroe | 6 | 6 | 6 | |||||||||||||||||||
| 2 | J McEnroe | 4 | 7 | 6 | |||||||||||||||||||||||
Nicklas Kulti was the defending champion, but lost in the first round this year.
Thomas Muster was the defending champion of the singles event at the Australian Men's Hardcourt Championships tennis tournament, but did not participate this year.
Andrei Chesnokov was the defending champion, but did not participate this year.
Andrei Chesnokov defeated Thomas Muster in the final, 7–5, 6–3, 6–3 to win the singles tennis title at the 1990 Monte Carlo Open.
Mats Wilander was the defending champion but lost in the third round to Alberto Mancini.
Jonas Svensson was the defending champion but lost in the quarterfinals to Horst Skoff.
Horst Skoff was the defending champion but lost in the second round to Glenn Layendecker.
Boris Becker was the defending champion but lost in the third round to Jan Gunnarsson.
Marc Rosset was the defending champion, but lost in the semifinals this year.
Horst Skoff was the defending champion, but lost in the final this year.
Emilio Sánchez was the defending champion, but lost in the second round to Francisco Roig.
Karel Nováček was the defending champion but chose to compete in Hilversum at the same week, winning the tournament.
Thomas Muster was the defending champion, but did not compete this year.
Thomas Muster was the defending champion, but lost in the semifinals to Fabrice Santoro.
Magnus Gustafsson was the defending champion, but lost in the second round to Tomás Carbonell.
Emilio Sánchez was the defending champion, but lost in the semifinal to Horacio de la Peña.
Horacio de la Peña was the defending champion, but lost in the third round to Francisco Clavet.
The 1991 PCzechoslovak Open was a men's tennis tournament played on Clay in Prague, Czech Republic that was part of the International Series of the 1991 ATP Tour. Jordi Arrese was the defending champion, but lost in the second round to Thomas Muster.
Kent Carlsson was the defending champion but was forced to forfeit the rest of the season, due to a knee injury that was suffered in August.
Thomas Muster was the defending champion, but lost in the quarterfinals to Guillermo Pérez Roldán.