OEYNHAUSEN, a town and watering-place of Germany, in the Prussian province of Westphalia, on the Werre, situated just above its confluence with the Weser, 9 m. W. from Minden by the main line of railway from Hanover to Cologne, with a station on the Löhne-Hameln line. Pop. (1905) 3894. The place, which was formerly called Rehme, owes its development to the discovery in 1830 of its five famous salt springs, which are heavily charged with carbonic acid gas. The waters are used both for bathing and drinking, and are particularly efficacious for nervous disorders, rheumatism, gout and feminine complaints.