Jacob Henriques de Castro Sarmento (6 May 1690 in Bragança, Portugal – 14 September 1762 in London) was a Portuguese estrangeirado, physician, naturalist, poet and Deist.

In order to escape the persecutions of the Portuguese Inquisition, Henrique — so-called as a Marrano, a Christian to the outside world, but privately a practicing Jew, — went into voluntary exile in London in 1720.

[3][4][5] Learning about quinine in London, Castro Sarmento developed a medicine known as Água de Inglaterra, which became popular in Portugal where malaria was still widespread in the southern part of the country.

Castro Sarmento corresponded with many scholars, among others with Prof. João Mendes Sachetti Barbosa of Lisbon, who reported to him the terrible earthquake that destroyed the capital of Portugal in 1755, and with the Jesuit Buenaventura Suárez, who communicated to him his astronomical observations made in Jesuit reduction of Paraguay.

[8] The literary activity of Castro Sarmento began with a treatise on vaccination, Dissertatio in Novam, Tutam, ac Utilem Methodum Inoculationis seu Transplantationis Variolorum (London, 1721; German translation, Hamburg, 1722; Supplement, London, 1731; anonymously, Leyden).