The 1998 Estoril Open was a tennis tournament played on outdoor clay courts. This event was the 9th edition of the Estoril Open, included in the 1998 ATP Tour International Series and in the 1998 ITF Women's Circuit. Both the men's and the women's events took place at the Estoril Court Central, in Oeiras, Portugal, from April 6 through April 13, 1998.
Alberto Berasategui defeated Thomas Muster, 3–6, 6–1, 6–3
Barbara Schwartz defeated Raluca Sandu, 6–2, 6–3
Donald Johnson / Francisco Montana def. David Roditi / Fernon Wibier, 6–1, 2–6, 6–1
Caroline Dhenin / Émilie Loit def. Radka Bobková / Caroline Schneider, 6–2, 6–3