Bridget Pastoor, the Progressive Conservative legislature member for Lethbridge-East, has announced she will not run in the next election.
Pastoor has spent 16 years in the public eye, first as an alderman in Lethbridge, and then as an MLA since 2004.
She was originally a Liberal, but crossed the floor in 2011 to join the PCs under then-premier Alison Redford.
Pastoor once volunteered for the Tories and said at the time she was crossing because she believed in Redford.
The 75-year-old won Lethbridge-East handily in the 2012 campaign.