| Honorific Prefix: | Professor |
| Sir John Lilleyman | |
| Office: | Professor of Paediatric Oncology, St Bartholomew's Hospital Medical College/Barts and The London School of Medicine and Dentistry |
| Term Start: | 1995 |
| Term End: | 2006 |
| Birth Name: | John Stuart Lilleyman |
| Birth Date: | 9 July 1945 |
Sir John Stuart Lilleyman (born 9 July 1945) is a British paediatric haematologist. His specialization is childhood leukemia and idiopathic thrombocytopenic purpura.[1]
Lilleyman contributed to the testing of leukemia treatment methods and conducted research on "thiopurine metabolism" in children with leukemia.[1]
He was president of the Royal College of Pathologists during the Alder Hey organs scandal.[1] During that time, he was vice-chairman of the Academy of the Medical Royal Colleges.[1]
In 2004, he became medical director of the National Patient Safety Agency (NPSA).[2]
In 1991, the Royal College of Pathologists awarded him its first Distinguished Service Medal for establishing the United Kingdom's system of pathology laboratory accreditation.[3] He was appointed president of the Royal Society of Medicine in 2004.[2]