The 1939 Christchurch South by-election held on 3 June was caused by the death of Ted Howard during the term of the 26th New Zealand Parliament. The by-election in the Christchurch South electorate was contested by Robert Macfarlane for Labour and Melville Lyons for National, with Macfarlane winning the election. At the time, Macfarlane was Mayor of Christchurch.

Ted Howard, born as Edwin John Harney, was a New Zealand politician of the Labour Party, and the father of cabinet minister Mabel Howard. He had been a prominent member of the New Zealand Socialist Party, a precursor to the Labour Party.