Born at Greenisland, Co Antrim, where his family had lived for many generations, on 4 January 1872, the only son and eldest child of Charles Johnstone, land owner, and Mary McCreavy, his wife. He was educated at the Belfast Academical Institution, and at Queen's College, Belfast, where he was a scholar in 1891, 1892, and 1894, Dunville student in 1895, and Coulter exhibitioner and first medallist at the BA examination. He served as house surgeon at the Royal Victoria Hospital as soon as he was qualified, was demonstrator of anatomy at Queen's College, and was appointed to a studentship in pathology under Professor Lorraine Smith in 1896. He then took postgraduate courses in London and Vienna, and on his return, having determined to devote himself to the diseases of women, acted as assistant to Sir John Byers from 1900. He was soon appointed surgeon to the Belfast Maternity Hospital, and in 1902 was elected assistant gynaecologist at the Royal Victoria Hospital, becoming surgeon in 1908 and professor of gynaecology at the University in succession to Sir John Byers in 1921. When the Parliament of Northern Ireland was established in 1921 Johnstone was chosen to represent Queen's University in the Ulster House of Commons. He did much good work in this position, and took an active part as a member of the Royal Commission which issued a report upon which the Education Act in Northern Ireland was afterwards based. His parliamentary record also included the chairmanship of the commission on local government services in Northern Ireland; this commission in 1927 issued a survey of the existing system, which revealed its limitations and outlined a comprehensive scheme of reform. He did equally good work at the British Medical Association which he joined in 1897. For seven years he was secretary of the Ulster branch, of which he was president in 1921, and in 1937 he was elected president of the Association when the annual meeting was held in Belfast. During his year of office he received the honour of knighthood. From 1927 until his death he represented Queen's University on the General Medical Council, and from 1934 he was a member of the Dental Board. He took a prominent part in the inception of the Royal College of Obstetricians and Gynaecologists, was a foundation Fellow, and was elected to the Council. In freemasonry he was always interested, was one of the founders and was the first master of the Queen's University Lodge. On 8 August 1906 he married Florence, daughter of the Rev G Magill, Presbyterian minister of Cliftonville. She survived him, but without children. He died at Newcastle, Co Down on 25 October 1938. Sir Robert Johnstone held a high position in the medical profession. He was loved and trusted by all his contemporaries, both for his social and professional attainments. Fostered by his friend and former master, Edward Russell, he had a sound knowledge of the classics and could read Greek and Latin poetry with pleasure. He was for two successive years captain of the Royal County Down. Golf Club. He early enlisted in the University Volunteer Force, and during the first world war he was engaged daily in its duties, without a commission and as a voluntary worker. Publications: Obstetrics and gynaecology, in Whitla's *Dictionary of treatment*, 6th edition, London, 1920. Caesarean section, with a record of 28 cases. *Trans Ulster med Soc* 1914-15, pp 99-114. Renal decapsulation in puerperal eclampsia. *Practitioner*, 1908, 80, 797.