Safdhar Rahim, 63, was seen at various points along the Bloor/Danforth line early Friday morning, bleeding from the leg.
Police say they were called at 1:10 a.m. about a bleeding man at Christie station. Minutes later they were told a man had been stabbed while getting off a train at Ossington.
Rahim, who is known to police, was then spotted on surveillance video, apparently injured, at Castle Frank station at about 1:33 a.m. and was last seen about ten minutes later, again on camera, back at Ossington.
Investigators at 14 Division say they found blood on a train and blood trails at the stations.
Police are not certain how he was injured but say they are concerned for his safety.
He is described as five-foot-five, with a medium build. He was last seen wearing a black baseball cap, a brown jacket and blue jeans.
Anyone with information is asked to contact police at 416-808-1400, or Crime Stoppers at 416-222-TIPS.