The Australian republic referendum held on 6 November 1999 was a two-question referendum to amend the Constitution of Australia. The first question asked whether Australia should become a republic, with a president appointed by Parliament following a bi-partisan appointment model which had been approved by a half-elected, half-appointed Constitutional Convention held in Canberra in February 1998. The second question, generally deemed to be far less important politically, asked whether Australia should alter the Constitution to insert a preamble. Since the early 1990s opinion polls had suggested that a majority of the electorate favoured a republic in principle. Nonetheless, the republic referendum was defeated.

The 1998 Australian Constitutional Convention was a Constitutional Convention which gathered at Old Parliament House, Canberra from 2 to 13 February 1998. It was called by the Howard government to discuss whether Australia should become a republic. The convention concluded with "in principle support" for an Australian republic and proposed a model involving appointment of the head of state by Parliament. The model was put to a referendum in November 1999 and rejected by the Australian electorate.