A by-election was held for the New South Wales Legislative Assembly electorate of Lismore on 12 September 1959 because Justice Sugerman in the Court of Disputed Returns declared that the 1959 Lismore election was void. Electoral officers failed to initial or sign 51 ballot papers, rendering those papers informal. Those electors had been prevented from casting an effective vote and therefore preventing from voting. As Jack Easter's margin at the election was only 2 votes, the errors may have affected the result of the election.