The Mühldorf–Simbach am Inn railway is a 39 km long, single-tracked, unelectrified main line in Bavaria in southern Germany.

Leaving Mühldorf station it runs in an east-west direction to the German-Austrian state border, where it joins the Innviertel Railway.

A pair of trains consisting of the ÖBB locomotive, BR 2016 "Herkules", and four IC coaches runs every morning from Linz to Munich and back again in the evening, stopping at just a few stations.

In addition, between Mühldorf and Linz a direct morning link to Austria and evening return has been established using DB Class 628 multiples which stop at most stations.

Another transfer task is carried out on work days between Mühldorf and Simbach in both directions by a Südostbayernbahn locomotive (DB Class 218).

The Austrian firm of Logistik- and Transport GmbH (LTE) runs a paraffin coke (Petrolkoks) train twice weekly wöchentlich einen Petrolkokszug between the Wacker works at Burghausen and Ziar and Hronom (Slovakia) via Bratislava.