Police say Alexandre Robillard was last seen around 8 a.m. on Feb. 26, in the area of College Street and Lansdowne Avenue.
He's described as white, five-foot-nine with short brown hair. He was last seen wearing a dark North Face Jacket, black Adidas track pants and a dark backpack.
Police believe he may be with Ibrahim Bayo, also 15, who was last seen in the same area.
He's described as black, five-foot-ten with a thin build. A photo for Bayo was not immediately available.
Anyone with information is asked to call 14 Division at 416-808-1400