The 1990 All-Ireland Under-21 Hurling Championship final was a hurling match that was played at O'Moore Park, Portlaoise on 9 September 1990 to determine the winners of the 1990 All-Ireland Under-21 Hurling Championship, the 27th season of the All-Ireland Under-21 Hurling Championship, a tournament organised by the Gaelic Athletic Association for the champion teams of the four provinces of Ireland.