Nationalist Senators Edward Millen, Herbert Pratten and Josiah Thomas were not up for re-election.
Nationalist Senators Thomas Crawford, Harry Foll and Matthew Reid were not up for re-election.
Nationalist Senators Robert Guthrie, James Rowell and William Senior were not up for re-election.
Uniquely, one of these was for a vacancy extending only until the new Senate assumed its place on 1 July 1920; this was the remainder of James Long's term that had been filled in the interim by Edward Mulcahy.
The fourth elected senator would thus serve only until 1 July 1920, whereupon his term would expire.
Nationalist Senators Richard Buzacott, Hugh de Largie and George Henderson were not up for re-election.