Todd Milne, head of security at Toronto General Hospital, said no one stopped the confident thieves when they put the piano on a dolly July 14 in the Peter Munk Wing and calmly walked out of the hospital with the instrument at 12:51 p.m., The Globe and Mail reported Tuesday.
Milne said the men told workers they were taking the piano for tuning.
"If you don't know anything about pianos, you don't know that the tuners come to the piano," he said. "I've been managing security since 1999, and have not experienced a theft as ballsy and as crazy as this one."
Milne said the piano was donated in 2006 and members of the Canadian Opera Company and other performers used it once a week to perform for cancer patients and their families.
Milne said police have been given images of the suspects taken by a security camera.