| Singles | |
|---|---|
| 1998 Majorca Open | |
| Champion |  Gustavo Kuerten |
| Runner-up |  Carlos Moyà |
| Final score | 6–7(5–7), 6–2, 6–3 |
| Draw | 32 |
| Seeds | 8 |
| Singles | |
|---|---|
| 1998 Majorca Open | |
| Champion | Gustavo Kuerten |
| Runner-up | Carlos Moyà |
| Final score | 6–7(5–7), 6–2, 6–3 |
| Draw | 32 |
| Seeds | 8 |
A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated.
Carlos Moyà (final) Àlex Corretja (second round) Álbert Costa (second round) Alberto Berasategui (second round)
Thomas Muster (semifinals)
Magnus Gustafsson (first round) Francisco Clavet (first round) Gustavo Kuerten (champion)Thomas Enqvist was the defending champion but lost in the second round to Jaime Yzaga.
First-seeded Marcelo Ríos defeated Richard Fromberg 4–6, 6–4, 7–6(7–3) to win the 1998 Heineken Open singles competition. Jonas Björkman was the champion but did not defend his title.
Sandra Cacic was the defending champion but lost in the quarterfinals to Tamarine Tanasugarn.
Steffi Graf was the defending champion but lost in the semifinals to Gabriela Sabatini.
Gabriela Sabatini was the defending champion but did not compete that year.
Henrieta Nagyová was the defending champion but lost in the final 6–4, 6–4 against Barbara Paulus.
Anke Huber was the defending champion but did not compete that year.
Pam Shriver was the four-time defending champion but lost in the final 6–2, 6–1 against Claudia Kohde-Kilsch.
First-seeded Ai Sugiyama was the defending champion and won in the final 6–3, 6–3 against Corina Morariu.
Iva Majoli was the defending champion but lost in the second round to Barbara Schett.
Amanda Coetzer was the defending champion but lost in the first round to Elena Tatarkova.
Juan Balcells was the defending champion but lost in the quarterfinals to Albert Montañés.
Sjeng Schalken was the defending champion and won in the final 6–3, 6–4 against Arnaud Clément.
Paradorn Srichaphan was the defending champion and won in the final 6–2, 6–4 against James Blake.
Camille Benjamin was the defending champion but lost in the semifinals to Terry Phelps.
First-seeded Martina Navratilova was the defending champion and won in the final 6–2, 6–3 against Chris Evert.
Yevgeny Kafelnikov was the defending champion but lost in the semifinals to Marc Rosset.
Michael Stich was the defending champion but lost in the first round to Scott Draper.
Yevgeny Kafelnikov was the defending champion but did not compete that year.
