A by-election was staged in the New South Wales Legislative Assembly district of Macquarie Fields on 17 September 2005. It was triggered by the resignation of sitting member and former minister Craig Knowles (Labor). The by-election was timed to coincide with two other state by-elections in Maroubra and Marrickville.
The by-election saw the Labor Party retain the seat with the election of candidate Steven Chaytor.