The section between Hemer and Iserlohn and the branch line from Hemer to Sundwig have been closed and dismantled.
The construction of its first inter-regional line by the Bergisch-Märkische Railway Company (Bergisch-Märkische Eisenbahn-Gesellschaft, BME) bypassed various nearby towns such as Iserlohn.
For over 100 years it ran from Letmathe via Iserlohn, Hemer and Menden to Fröndenberg.This stretch has remained as a single-track branch line, in contrast to the Ardey Railway, but it has been electrified since .Since the dismantling of the line to Hemer, Iserlohn station has become a curiosity, as it is the terminus of two different lines.In November 2007, the Hemer transport committee decided that it no longer wish to pursue this idea because in the opinion of experts no rail services would result.Instead, it considered converting the line into a cycle path.
Six years later, the remaining section in the city center of Iserlohn, which was nearly one and a half km-long, was closed on .During the early planning for Landesgartenschau Hemer 2010 (State Garden Show Hemer 2010) consideration was given to re-opening the line.In the second half of the 19th Century the BME began to provide connections from its main line, the Elberfeld–Dortmund railway, to isolated places in the western Sauerland. This is also locally called the Iserlohner Bahn (Iserlohn Railway).This later developed into the Hönne Valley Railway to Neuenrade.
Plans for the extension of the line from Menden to Hemer go back to the 1860s.
The line from Fröndenberg to Menden was not electrified.
It is now operated as a two-track branch line as part of the Hönne Valley Railway to Neuenrade.
Letmathe-Dechenhöhle station was built close to the show cave.
Eight years later the BME built another branch line, this time starting from Fröndenberg station via its Upper Ruhr Valley Railway to Menden (Sauerland) station. This line was extended initially by Rödinghausen by the then königlichen Eisenbahndirection Elberfeld (Royal railway division of Elberfeld) of the Prussian state railways (PSE) in 1878.