or Van Heurn, (John), a learned physician, was born at Utrecht in 1543; and studied at Louvain, Paris, Padua, and Pavia. At his return to his native country he became magistrate of Amsterdam; after which he was professor of physic at Leyden, and rector of the university of that city, where he died in 1601. He wrote, among other works, several treatises on the diseases of different parts of the body, and several commentaries on the works of Hippocrates.—Otto Heurnius his son was also professor of physic at Leyden, and wrote some books.