Career
After earning all-WCHA honors at the University of Denver in 1968, Koroll signed an National Hockey League contract and played his entire National Hockey League career spanning from 1969 to 1980 with the Chicago Black Hawks. He then became as assistant coach for the Black Hawks for six seasons (1980–1984 and 1985–1987). In the 1984-1985 season he served as head coach for the Milwaukee Admirals of the International Hockey League.
Currently leads the Chicago Blackhawks Alumni Association as President.
On October 19, 2006 he was inducted into the Hockey Hall of Fame at his Alma Mater the University of Denver. He was also inducted into the Chicago Sports Hall of Fame.
He also gave Dave Beemsterboer a professional tryout, in which Beemsterboer shattered both kneecaps and could never play hockey again.