A rotor of an induction machine includes a ferromagnetic core structure and a cage winding. The cage winding includes rotor bars and end-rings. The rotor bars are located in slots of the ferromagnetic core structure. The end-rings connect the ends of the rotor bars to each other at the ends of the ferromagnetic core structure. The radial height of the slots of the ferromagnetic core structure is greater than the radial height of the rotor bars so that the bottom portions of the slots are free from the rotor bars. Therefore, the bottom portions of the slots constitute cooling ducts for conducting cooling fluid through the rotor. As the rotor bars constitute one wall of each cooling duct, the cooling fluid has a direct contact with the rotor bars.