Born 19 January 1837 in Philadelphia, the son of William Williams Keen and Susannah Budd, his wife. His father was a leather merchant and he was the eighth in linear descent from Johan Keyn, a Swede who came to America in the train of the Swedish governor Johan Printz in February 1643. His mother was descended from the Budds of Montacute, Somersetshire, where her ancestor was vicar of St Catherine's. William Keen was educated at Newton Grammar School, Philadelphia, and at the Central High School which he left in 1853. He graduated from Brown University, Providence, Rhode Island in 1859 and received the degree of doctor of medicine from Jefferson Medical College, Philadelphia, in 1862. He then determined to specialize in surgery, and during 1866-75 lectured on pathological anatomy in Jefferson Medical College, where he was subsequently professor, and on artistic anatomy at the Pennsylvania Academy of the Fine Arts, and was a teacher at the Women's Medical College from 1884 until 1889. In 1861 he served as an assistant surgeon in the United States Army. In 1864, in association with Dr Weir Mitchell and from experience gained during the Civil War, he laid down those principles of the treatment of gunshot wounds of nerves which formed the starting point of the methods amplified during the war of 1914-18. In July 1893 Keen operated upon President Cleveland. The operation was undertaken during a serious financial crisis in the United States when every action of the President was subjected to the closest scrutiny. Yet in spite of this Dr Bryant and Dr Keen succeeded in eluding the vigilance of the reporters and removing nearly the whole of the left upper jaw for cancer. The operation was performed on board the yacht *Oneida* steaming at half speed up the East river at New York and even his colleagues in the government were ignorant that anything had been done to their President. The anaesthetic was given by a dentist. Within a month the President attended a meeting of the Senate and spoke. He survived for fifteen years and the fact of the operation having been done was not disclosed for twenty-four years. Keen married in 1867 Emma Corinna Borden, of Fall River, Massachusetts. She died in 1886 leaving four daughters who married in their turn, and at the time of Dr Keen's death there were thirteen grandchildren and eleven great-grandchildren living. He died at his home, 1520 Spruce Street, Philadelphia, after a short illness, on 7 June 1932, aged 95, and his body was cremated after a funeral service at the First Baptist Church. Keen exercised a powerful influence for good upon American surgery and took an active part in municipal affairs during his long life. Short of stature with twinkling blue eyes, he retained almost to the end his vivid interest in life and in science. A man of deep religious feeling he was throughout his life an abstainer and a non-smoker. He was active in promoting the cause of vaccination, and it was mainly due to his advocacy that experiments upon living animals are less hedged round by restrictions in the United States than they are in this country. He was a frequent visitor to England and in later life was accustomed to bring with him many members of his family. Both in the United States and in Europe he was honoured and respected as a representative surgeon. Honours came to him from many nations. At home he was president of the American Medical Association, of the College of Physicians of Philadelphia, and of the American Surgical Association. Abroad he was an honorary Fellow of the Royal Colleges of Surgeons of England, of Edinburgh, and of Ireland, a member of the Deutsche Gesellschaft fur Chirurgie, of the Società italiana di Chirurgia, and of the Académie de Médecine of France. The Boston Medical Society awarded him the Bigelow medal. He was also the holder of the Colver-Rosenberger medal, and on his ninety-second birthday he received the gold medal of the Pennsylvania Society of New York for meritorious and distinctive services. He was president of the Société internationale de Chirurgie in 1920. He was decorated with the Cross of the Legion of Honour and with the Belgian Order of the Crown. There is a photograph of him in uniform in the Honorary Fellows' album, which is a good likeness. Publications: *Surgical complications of typhoid fever*. Philadelphia, 1898. *Animal experimentation and medical progress*. Boston, 1914. *Medical research and human welfare*. Boston, 1917. *Treatment of war wounds*. Philadelphia, 1917; 2nd edition, 1918. *Addresses and other papers*. Philadelphia, 1905. *The surgical operations on President Cleveland in* 1893. Philadelphia, 1907. Selected papers and addresses. Philadelphia, 1923. Editor of *American text-book of surgery*. Philadelphia, 1892; 2nd edition, 1895; 3rd edition, 1899; 4th edition, 1904. The book attained a world-wide reputation. *Surgery, its principles and practice*, 8 vols. Philadelphia, and London, 1906-21; translated into Spanish, vols 1-6, Barcelona, 1910-16. See also the *Index Catalogue* of the Surgeon General's Library 1886, 7, 362; 1903, 2nd ser, 8, 599-601; 1928, 3rd ser, 7, 138. The College Library contains a large collection of his papers.