Later, the lines to the north-east to the port (Seehafen) of Rostock and to the south to the town of Güstrow via Schwaan were included in the S-Bahn network.

Until 2014 the rolling stock mainly consisted of push–pull trains with Waggonbau Görlitz double-deck coaches.

Line S1 runs west of the Unterwarnow from Warnemünde through the built-up areas of Lichtenhagen, Lütten Klein, Evershagen and through the industrial areas of Marienehe and Bramow between Kröpeliner-Tor-Vorstadt and Hansaviertel to Rostock Hauptbahnhof, located in the south of the Steintor-Vorstadt.

There has long been dense suburban traffic on the line between Rostock Hauptbahnhof and the seaside resort of Warnemünde.

In the 1960s, a route to the west of the urban motorway to Warnemünde was considered initially, but these plans were not pursued because of the high construction costs.

A trip from Rostock to Warnemunde cost 50 Pfennig, while for shorter distances the normal Deutsche Reichsbahn fare applied.

[2] The route to Lütten Klein was extended in the following years to the north and reconnected to the old track south of Warnow-Werft station.

After Die Wende (the change) in the 1990s, the volume of traffic during the peak hour fell as, on the one hand, most large companies reduced staff or were closed and, on the other, the residential areas along the S-Bahn line lost population.

In 2009, the state of Mecklenburg-Vorpommern developed plans to operate a "Warnow" network, which in addition to the Rostock S-Bahn would include the Wismar–Rostock–Tessin, the (Bad Doberan)–Rostock–Graal-Müritz and the Wismar–Ludwigslust lines.

In mid-May 2012, the Ministry of Energy, Infrastructure and Regional Development of Mecklenburg-Vorpommern announced that in the future line S4 would not run to the port of Rostock.

The Rostock City Council contradicted this and called for an extension of the S-Bahn line to the ferry terminal in the port.

For a long time services between Rostock and Warnemünde were operated with double-deck push-pull trains.

Since 9 October 2013, starting with line S3, 23 Bombardier Talent 2 electric multiple units have gradually replaced the old double-deck railcars.