1990 Estoril Open – Men's singles

This was the first edition of the event.

Emilio Sánchez won in the final 6–3, 6–1, defeating Franco Davín.

Seeds

 * 1) 🇺🇸 Jay Berger (Quarterfinals)
 * 2) 🇦🇷 Martín Jaite (first round)
 * 3) 🇪🇸 Emilio Sánchez (champion)
 * 4) 🇪🇨 Andrés Gómez (first round)
 * 5) 🇦🇹 Thomas Muster (quarterfinals)
 * 6) 🇵🇪 Jaime Yzaga (first round)
 * 7) 🇦🇷 Guillermo Pérez Roldán (first round)
 * 8) 🇪🇸 Sergi Bruguera (second round)