Crews from Greater Manchester Fire and Rescue Service were called to the three storey maisonette on Middleton Road in Chadderton at around 8.40am on Tuesday.
Fire fighters from Oldham, Chadderton and Hollins entered the flat and discovered the man unconscious and suffering from burns and smoke inhalation.
He was rushed to hospital for treatment.
Two other men were also rushed to hospital after being rescued suffering from smoke inhalation.
An investigation has now been launched into the cause of the blaze which remains a mystery.
