Victoria Chiechi, 38, was last seen on July 20.
She left her Mousseau Street home around 6 p.m. on her bike, without her wallet or any other belongings.
Longueuil police spokesperson Patrick Barrière said he hopes a man she met at a store earlier that day will be able to help with the investigation.
"We don't know if he is related to her family, a known friend or a stranger that she met at that place," he said.
Anyone with information should call Info-Crime at (514) 393-1133.