Flen is a locality and the seat of Flen Municipality, Södermanland County, Sweden with 6,229 inhabitants in 2010.
Flen evolved as a railway junction and got the title of a city in 1949. Since 1971 it is the seat of the much larger Flen Municipality.
Other things which made Flen famous is " Violen från Flen", a song written by Ulf Peder Olrog in the 1940s. The town also plays an important role in " Du ringde från Flen", 1992 dansband song by Grönwalls. The town is also mentioned in the Kent songs "Flen/Paris" on the 2005 EP " The Hjärta & Smärta EP" and "Ensam lång väg hem" on the 2010 album " En plats i solen".
Flen is also famous for having the world's northernmost vineyard, in Blacksta.