The 1998–99 Irish League Cup (known as the Coca-Cola League Cup for sponsorship reasons) was the 13th edition of the Irish League Cup, Northern Ireland's secondary football knock-out cup competition. It concluded on 4 May 1999 with the final.
Linfield were the defending champions after their fourth League Cup win last season; a 1–0 victory over Glentoran in the previous final. This season they became the first club ever to successfully defend the trophy. In a repeat of the previous final, Linfield once again came out on top with a 2–1 extra time victory against Glentoran in the final, lifting the cup for the fifth time and condemning the Glens to defeat in the final for the third season running, which is a record for successive final defeats in the competition that still stands.[1][2][3]
The competition was re-structured this season, allowing only the 10 top-flight clubs and the 8 second-tier clubs to enter. This reduced the number of clubs taking part from 32 down to 18.