See also: List of longest-serving members of the Australian Senate
The first House of Representatives was elected on 30 March 1901. All the members elected to that First Parliament therefore had equal seniority. It follows that there could not be a "longest-serving member" until only one member from the First Parliament was still in the House. That occurred on 8 April 1935 with the death of David Watkins .
Since that date the longest-serving members of the House of Representatives have been:
Between 31 July 1963 and 29 September 1969 several members had equal lengths of service, having all been elected at the 1934 election. They were: Robert Menzies (first elected 15 September 1934, resigned 16 February 1966), Joseph Clark (first elected 15 September 1934, retired 29 September 1969) and Sir John McEwen.
Between 10 November 1977 and 19 September 1980, two members had equal lengths of service, having both been elected at the 1949 election. They were: Hon Clyde Cameron (first elected 10 December 1949, retired 19 September 1980) and Rt Hon Sir William McMahon.
Between 4 January 1982 and 21 April 1983, several members had equal lengths of service, having all been elected at the 1955 election. They were: Malcolm Fraser (first elected 10 December 1955, resigned 31 March 1983), Billy Snedden (first elected 10 December 1955, resigned 21 April 1983) and Sir James Killen