Sidney Harris Cox Martin FRCP FRS (8 April 1860, Jamaica – 22 September 1924) was a British physiological chemist, physician, and medical school professor. ^[1]

Sidney Martin was the second son of John Ewers Martin (1826–1893), who married Matilda Elizabeth Slayter (b. 1833) in August 1857 in Kingston, Jamaica. Sidney Martin graduated in 1878 with a B.Sc. from University College London,^[2] where he was influenced by Ray Lankester.^[3] Sidney Martin studied medicine at the University College London, where he learned physiology and experimental pathology from Sanderson, and qualified M.R.C.S. in 1882.^[1] Martin then visited Vienna to study medicine and returned to England to take junior appointments at Middlesex Hospital and at the City of London Hospital for Diseases of the Chest (renamed in 1937 the London Chest Hospital and closed in 2015).^[2] He graduated in 1883 M.B.,B.S. Lond. and received in 1884 his M.D. (higher medical doctorate).^[1] From 1883 onward he worked in physiology at the laboratory of Schafer at University College London.^[3] At the City of London Hospital for Diseases of the Chest he was an assistant physician from 1888 to 1890. At University College Hospital, he was an assistant physician from 1890 to 1898 and a full physician from 1898 until his death in 1924. From 1892 to 1900 he also held an appointment as assistant physician at Brompton Hospital.^[2] At University College London he was from 1895 to 1907 professor of pathology and, simultaneously, from 1902 to 1907 professor of clinical medicine; after the reorganisation of University College Hospital he held the same positions there. During WW I he worked in the 3rd London General Hospital.^[2] From the summer of 1923 until his sudden death in 1924, he chaired the executive committee of the Imperial Cancer Research Fund.^[1]

Martin wrote a textbook on diseases of the stomach and a manual of pathology for students.^[2] In 1895 he contributed a 96-page appendix to a report by the First Royal Commission on Tuberculosis.^[1] He contributed articles on tuberculosis^[4] and (the now discredited concept of) ptomaine poisoning^[5] to Clifford Allbutt's A System of Medicine. Martin also contributed to the 3rd edition of Quain's Dictionary of Medicine^[6] and to Gibson's Textbook of Medicine.^[7]

He gave the Goulstonian Lectures in 1892,^[8][9][10] the Croonian Lectures in 1898,^{[11][12][13][14]} and the Lumleian Lectures in 1915.^[3] On 1 March 1909 he delivered the third of the Lettsomian Lectures to the Medical Society of London.^[15]

Martin was elected in 1891 a Fellow of the Royal College of Physicians and in 1895 a Fellow of the Royal Society.^[3]

Martin was married and had a daughter.^[2] He was a member of the Savile Club.^[16]