Colonial elections were held in South Australia from 9 April to 23 April 1890. All 54 seats in the South Australian House of Assembly were up for election.

Sir John William Downer, KCMG, KC was an Australian politician who served two terms as Premier of South Australia, from 1885 to 1887 and again from 1892 to 1893. He later entered federal politics and served as a Senator for South Australia from 1901 to 1903. He was the first of four Australian politicians from the Downer family dynasty.