Ashton-under-Lyne by-election may refer to one of five by-elections held in the British House of Commons constituency of Ashton-under-Lyne, in Lancashire:
1920 Ashton-under-Lyne by-election 1928 Ashton-under-Lyne by-election 1931 Ashton-under-Lyne by-election 1939 Ashton-under-Lyne by-election 1945 Ashton-under-Lyne by-election
See also Ashton-under-Lyne (UK Parliament constituency)