Federal elections were held in Australia on 5 May 1917. All 75 seats in the House of Representatives and 18 of the 36 seats in the Senate were up for election. The Nationalist Party of Australia (a result of a merger between the Commonwealth Liberal Party and National Labor Party) was in power and led by Prime Minister of Australia Billy Hughes who was defending his new government against his old party, the Australian Labor Party (ALP) now led by Frank Tudor.
Hughes, had become Prime Minister at the head of the ALP when Andrew Fisher retired in 1915. The Australian Labor Party split of 1916 over World War I conscription in Australia had led Hughes and 24 other pro-conscription Labor MPs to split off as the National Labor Party, which was able to form a minority government supported by the Commonwealth Liberal Party, led by Joseph Cook.
The newly formed Nationalists won a decisive victory, securing the largest majority government since Federation. The ALP suffered a large electoral swing against it, losing almost seven percent of its vote from 1914. The swing was magnified by the large number of former Labor MPs who followed Hughes out of the party.