Macleod returned to Scotland in 1928 to become Regius Professor of Physiology at Aberdeen University (in succession to his former teacher, John Alexander MacWilliam who retired in 1927) and later Dean of the University of Aberdeen Medical Faculty. Between 1929 and 1933 he was also a member of the Medical Research Council. He wrote a report on the discovery in 1922 to explain his side of the story, but otherwise refrained from active involvement in controversy about credit. Banting hated him passionately, and the two never spoke again.