John William Thomson Walker was born at Newport, Fife on 6 August 1871, the second child and second son of John H Walker, chairman of the Caldrow jute works, Dundee, and Isabella Thomson, his wife. He was educated at the Dundee High School and at the Edinburgh Institution. He then matriculated at the University of Edinburgh, where he won medals and prizes in chemistry, physiology, gynaecology, and medicine. He served the post of house surgeon at the Glasgow Royal Infirmary and at the Dundee Royal Infirmary. Proceeding to Germany for a postgraduate course he studied at Jena and Vienna where, coming under the influence of Professor Zuckerkandl, he became interested in urology. He was appointed pathologist to the Paddington Green Children's Hospital on his return to England, and in December 1891 was appointed surgical assistant to E Hurry Fenwick at St Peter's Hospital for Stone in Henrietta Street, Covent Garden, becoming assistant surgeon in 1893, and remaining upon the full staff until ill-health compelled him to retire in 1932. He was a Hunterian professor at the College in 1907. In 1919 he was appointed senior urologist and lecturer on urology at King's College Hospital, a position which led him to retire from the office of surgeon to the Hampstead General Hospital, which he had held for many years. At one time he held a commission in the London Scottish regiment but resigned before 1914, and during the European War he was attached, with the rank of temporary captain, RAMC, to King George V Red Cross Hospital, to King Edward VII Hospital for Officers, and as consulting urologist to the Star and Garter Home for disabled soldiers. Ill-health compelled him to retire from practice in 1929, and he lived at Burntwood, Goring-on-Thames. He married in 1909 Isabella, daughter of Sir Michael Nairn, Bt. She survived him with a son and a daughter. He died suddenly on 5 October 1937 at Aviemore, Inverness-shire. Sir John Thomson Walker was a leader in modern urology and a fitting successor to such a man as Sir Henry Thompson, for he was highly cultivated, had many interests, and was insistent that a specialist should have had a training in general surgery. His operative skill was of a high order and was especially shown in connexion with removal of the prostate. He was able to reduce the mortality which had previously been high to two per cent. Amongst his patients were Philip Snowden, David Lloyd George, and Robert Baden Powell. He occupied many important positions and received many honours. He was president of the fifth congress of the Société internationale d'Urologie, president of the Medical Society of London in 1933, where he had delivered the Lettsomian lectures in 1930, and was Silvanus Thompson lecturer in 1926 at the Roentgen Society. His international reputation was attested by his membership of the urological societies in America, France, Germany, Austria, Spain, Portugal, Hungary, and of the Academy of Medicine of Rome. He was fond of shooting and gardening, but during his professional life he was chiefly interested in collecting prints of medical men. He succeeded in amassing about 2,500, all in a first-rate state. He hyphened his name in 1922, when he received the honour of Knight Bachelor. Publications: The surgical anatomy of the operation of suprapubic prostatectomy. *Arch Middx Hosp* 1905, 4, 27. On the surgical anatomy of the prostate. *J Anat* 1906, 40, 189. The Hunterian lectures on the renal function in its relation to surgery. *Lancet*, 1907, 1, 711 and 792. *Surgical diseases and injuries of the genito-urinary organs*. London, 1914; 2nd edition, by Kenneth Walker, 1936.