Barend Joseph Stokvis (Dutch pronunciation: [ˈbaːrəɲ ˈtɕoːsəf ˈstɔkfɪs]; 16 August 1834 – 29 September 1902) was a physician and professor of physiology and pharmacology at the University of Amsterdam.

[5] He studied medicine in Amsterdam and at the University of Utrecht under Franciscus Donders and Jacobus Schroeder van der Kolk,[3][6] obtaining a doctorate on a dissertation on hepatic glucose production in diabetes in 1856.

[6] In 1867, the Brussels Academy awarded a gold medal to Stokvis for an essay on the development of albuminuria, a kidney disorder in which the protein albumin can be detected in the urine.

[11] His prolific output, mainly in chemical pathology,[3] included research into the metabolism of glycogen, uric acid, and urea; studies into an epidemic of cholera in Amsterdam; the toxicity of Atropa belladonna (deadly nightshade); various pigmented substances in the blood (including porphyrins); the nature of the heart sounds; and several contributions in tropical medicine,[6] in which he was considered an expert.

[1][12] Stokvis observed the unusual dark red urine, discovered that it contained porphyrins, and coined the name "porphyria" for the condition.

[12][13] The Swedish chemist Olof Hammarsten further analysed red compound found in the urine of the patients with sulfonal-related porphyria attacks, labeling it "haematoporphyrin".

[13] Stokvis' most important work was judged by his contemporaries to be his three-volume "Voordrachten over Geneesmiddelenleer" ("Speeches on Pharmacology", soon translated into the French "Leçons de Pharmacotherapie"), which appeared shortly before his death.

[4] Together with Samuel Siegmund Rosenstein, professor of medicine in Leiden, he was a supporter of Aletta Jacobs, the first woman to qualify as a doctor in the Netherlands.