So far it appears to be that Uchiha Madara is immortal in the series, because of the superhuman Mangekyo sharingan in his eyes.
Through a Genjutsu cast by Itachi, Sasuke sees that Madara stole his younger brother's eyes when he was slowly going blind from the Mangekyo's advanced power.
Itachi said that Madara's light would never again fade, meaning he'll have eternal sight and sharingan. He is supposedly over 80 years old as well, according to Madara's own
Words in the manga.
