The1998–99 Irish Cup was the 119th edition of theIrish Cup,Northern Ireland's premierfootball knock-out cup competition. The last match was played on 20 April 1999. The final did not take place this year, for only the third time in the competition's history.^[1]

Glentoran were the defending champions after winning their 17th Irish Cup last season, with a 1–0 win overGlenavon in the 1998 final. This season they reached the sixth round, where they were defeated 2–1 byCliftonville.

Portadown won the cup for the second time, after Cliftonville were disqualified from the competition for fielding an ineligible player in the semi-final replay againstLinfield. Linfield were not permitted to replace Cliftonville in the final, so Portadown were awarded the cup without the final being played.^[2][3]

The following teams were given byes into the first round:1st Bangor Old Boys,Ballynahinch United,Bangor Amateurs, Civil Service,Dromara Village,Dromore Amateurs, Drummond United,Hanover,Harland & Wolff Sports,Killymoon Rangers,Larne Tech Old Boys,Laurelvale,Magherafelt Sky Blues,Portstewart,Queen's University,Rathfriland Rangers,Seapatrick,Sirocco Works,UUJ andWellington Recreation.

On 29 April 1999,Cliftonville were disqualified from the competition for fielding an ineligible player in the semi-final replay againstLinfield. The player in question had played for a junior club in an earlier round and was therefore ineligible. However, Linfield's protest came more than 48 hours after the tie (the usual deadline for protests), and as a result theIFA did not allow them to take Cliftonville's place in the final.Portadown were therefore awarded the cup without the final taking place.^[3]

• Irish Cup seasons
• 1998–99 in Northern Ireland association football cups

• Articles with short description
• Short description matches Wikidata