Emeritus Professor Quak is currently Emeritus Professor of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore; Emeritus Consultant, Department of Paediatrics, Khoo Teck Puat-National University Children's Medical Institute, National University Hospital. He is an emeritus consultant with the Division of Paediatric Gastroenterology, Nutrition, Hepatology and Liver Transplantation and the senior paediatric hepatologist of the Paediatric Liver Transplant Programme at NUH.

He graduated from the University of Singapore in 1976 and subsequently attained higher academic qualifications including Master of Medicine in Paediatrics and Doctor of Medicine from National University of Singapore. He obtained his postgraduate training in gastroenterology/hepatology at the Hospital for Sick Children in Birmingham, UK.

He is fully registered for Paediatric Medicine since 1977 and is a Specialist Registrar for Paediatric Medicine. He also obtained the Fellowship of Royal College of Physician, Glasgowand was a founder member of the Royal College of Paediatricians and Child Health, UK. 

He was also the founder President of the College of Paediatrics and Child Health, Singapore. He has been practising as a paediatrician since 1979 and his special interests are in children with abdominal pain, diarrheal diseases and childhood cholestasis. He is actively involved in teaching both undergraduate and postgraduate students.

For his outstanding and long-time contribution towards the development of Paediatric Gastroenterology and Hepatology, Emeritus Professor Quak Seng Hock is awarded the Emeritus Consultant Award 2013. He is also the recipient for the National Medical Excellence Awards 2014 (National Outstanding Clinician Mentor Award).