A by-election was held for the New South Wales Legislative Assembly electorate of Upper Hunter on 15 April 1861 because of the resignation of John Robertson. Roberston had resigned as Premier on 9 January 1861 to concentrate on the passage of the Robertson Land Acts, which would open up the free selection of Crown land. The bills were passed by the Legislative Assembly on 26 March 1861, and Robertson resigned to be appointed to the Legislative Council to ensure their passage into law.