Tienen is a city and municipality in the province of Flemish Brabant, in Flanders, Belgium. The municipality comprises Tienen itself and the towns of Bost, Goetsenhoven, Hakendover, Kumtich, Oorbeek, Oplinter, Sint-Margriete-Houtem and Vissenaken.
On 1 January 2017 Tienen had a total population of 34,365. The total area is 71.77 km² which gives a population density of 444 inhabitants per square kilometre.