[13] In 1973, after 3 years of medical practice, Lee went to New Zealand to pursue research, obtaining his PhD from the University of Auckland in 1978.

[13][15] Lee's career began at Queen Mary Hospital, where he worked for 3 years after receiving his MBBS in 1970.

[5] After his PhD, Lee became a consultant in gastroenterology and stayed at different institutions in Auckland, Sydney, Melbourne, London and Boston.

Eventually, he was appointed Cyrus E. Rubin Endowed Chair,[10] and became the Head of the Division of Gastroenterology at the Department of Medicine in 1995.

[1] Lee returned to the University of Hong Kong in 2008, taking up the position of Dean of the Li Ka Shing Faculty of Medicine.

[1][13] The Faculty at that time was besieged by various issues, most notably the scandal of former Dean of Medicine Shiu-kum Lam.

From 2003 to 2009, Lam defrauded HKU donors by making them pay HKD3.8 million to his private company, and transferred most of the amount to his personal account.

[36] Lee retired in August 2013, when his 5-year term as Dean ended,[7] and left the Board of the Hospital Authority.