Born in London on 2 October 1865, the eldest son of Dr James Scott Sequeira and Maria Rosina Rackwitz, his wife. He belonged to the sixth medical generation of his family in direct paternal descent. His great-grandfather, in the third medical generation, Isaac Henrique Sequeira, MD Leyden 1758, LRCP London 1771, was physician to the Prince Regent of Portugal in exile in London during the Napoleonic wars (see *Munk's Roll of the RCP* 2, 291). J H Sequeira was educated at King's College School and the London Hospital, which he entered with a scholarship in 1884; he took honours in materia medica at the intermediate examination in 1887 and in medicine and obstetric medicine at the MB 1890; he won the Hutchinson prize in 1893. He served as demonstrator of anatomy to Arthur Keith and Frederic Wood Jones, and was medical registrar and medical tutor for two years each. He had intended to practise surgery and took the Fellowship in 1893, but as there was no immediate surgical vacancy he developed his interest in dermatology, which began while he was house physician to Sir Stephen Mackenzie. He became MD 1891 and MRCP 1893, and further equipped himself by working with Leopold Freund and Eduard Schiff in Vienna, and with Niels Finsen at Copenhagen in 1900. He was appointed the first physician in charge of a special skin department at the London Hospital, being allowed one bed in each medical ward. He translated Finsen's book *Phototherapy* in 1901, and through the munificence of Queen Alexandra, herself a princess of Denmark, the first Finsen lamp in England was set up in Sequeira's department that year. He established and developed a complete skin and phototherapy department in the hospital, and was elected consulting physician to it on his retirement in 1927. He was a pioneer of X-rays and radium, advocating as early as 1905 the use of radium in the treatment of malignant disease, and was a lifelong sufferer from the effects of irradiation. He introduced X-ray epilation for ring-worm, and the carbon arc-light bath in the treatment of lupus. He was a skilled clinical photographer; and his Thursday morning teaching clinics were renowned. During the first world war Sequeira was a consultant in dermatology to military hospitals in London. He took a leading share in the scientific work of professional and public bodies. He was president of the dermatological section of the Royal Society of Medicine in 1925-27, and a Councillor of the Royal College of Physicians 1927, having been elected FRCP in 1905. He was chairman of the executive committee of the Society for the Prevention of Venereal Disease, and a member of Lord Trevethin's Committee on Venereal Disease. It was largely through his advice to Sir Arthur Newsholme that the Ministry of Health established venereal disease clinics throughout the country. He was a corresponding member of the Danish, French, and Japanese dermatological societies. Sequeira retired from all his London activities in 1927, when he was 62, and settled at N'Gong in Kenya, British East Africa, where he at once took on a new range of medical and public work. He was president of the Kenya branch of the British Medical Association in 1930-31 and 1933-34. He drew attention to the bad health conditions in the native reserves; he made a special study of leprosy; and he criticized the unification of the colonial services, which had led to the transfer of officers from one environment to another, in every respect divergent, where their previous experience was useless. During the war of 1939-45 he served as honorary consultant in dermatology to the East African forces. Sequeira's diminutive but dynamic personality was remarkable in dignity and kindliness; his short square figure carried a leonine head, with thick white hair and wide blue eyes. He was an amateur of music. Sequeira married in 1903 Helen Adams; there were no children of the marriage. He died in Kenya on 24 November 1948, aged 83, survived by his wife and their two adopted children. His brother, W H S Sequeira, MRCS, LRCP was succeeded by his son P J L Sequeira, MB BS, who carried the medical tradition to the seventh generation. Publications: *Phototherapy*, by Niels Finsen, translated and edited, London, 1901. Use of radium in the treatment of malignant disease. *International Congress of Surgery*, 1905. Tuberculosis of the skin. Allbutt's *System of medicine*, 1911. *Diseases of the skin*, with J T Ingram and R T Brain. London, 1911; 5th edition, 1947; Spanish translation, 1926. Public health in the tropics, especially Kenya, Chadwick lecture. *E Afr med J* 1932, 9, 59-78. Editor of the *British Journal of Dermatology*, 1911-15, and of the *East African medical Journal*.