Franz Riegel (9 February 1843 – 26 August 1904) was a German internist and gastroenterologist who was a native of Brückenau.
He studied medicine at the University of Würzburg, and following graduation furthered his studies in Vienna with Johann von Oppolzer (1808–1871). Afterwards he returned to Würzburg as an assistant to Heinrich von Bamberger (1822–1888), and later Carl Gerhardt (1833–1902). In 1871 he was a lecturer of experimental pathology at the University of Würzburg, and in 1874 became director of the Cologne city hospital. In 1879 he was appointed to the chair of medicine at the University of Giessen, where he would remain until his death in 1904.
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