The 1984 NBL season was the sixth season of the National Basketball League (NBL). With the Melbourne Tigers joining the competition, the league's number of teams increased to 17, with nine teams in the Eastern Division and eight teams in the Western Division. The regular season began on 3 February and ended on 17 June. The finals began on 22 June with the divisional finals before concluding on 1 July with the NBL Grand Final.