The 28-year-old of Eganville, Ont., set a Canadian record with a time of one minute 57.02 seconds, but was passed just before the finish line by Kenya's Margaret Wambui and denied a spot on the podium.
Caster Semenya of South Africa won gold in 1:55.28, followed by Francine Niyonsaba of Burundi in 1:56.49 and Wambui in 1:56.89.
Earlier, Nathan Brannen of Cambridge, Ont., was 10th in the men's 1,500 final.
Kenya's Margaret Nyairera Wambui, Britain's Lynsey Sharp, Belarus' Maryna Arzamasava, Canada's Melissa Bishop, Burundi's Francine Niyonsaba, and South Africa's Caster Semenya compete in the women's 800 metre final at the Rio 2016 Olympic Games at the Olympic Stadium in Rio de Janeiro on Saturday. (Photo: Eric Feferberg/AFP via Getty Images)
Bishop raced to gold at last summer's Pan American Games, then captured silver at the world championships in Beijing as part of Canada's historic eight-medal performance there.
She arrived in Rio in top form, having broken her own Canadian record in Edmonton in her last race before the Games.
She dedicated her run in Rio to the man she lovingly calls "Big Dawg,'' her longtime coach Dennis Fairall.
The coaching icon is battling progressive supranuclear palsy, a degenerative condition that has no cure. The 63-year-old was diagnosed almost three years ago with PSP, which is the deterioration of cells in the brain that control body movement and thinking.
Semenya, meanwhile, has thoroughly dominated the 800 this season, and cruised through the semifinal with the fastest time. The silver medallist in London four years ago is at the centre of a raging controversy about women with high levels of testosterone, and whether they should be permitted to compete.
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