A double-track line was continued via Postojna, Pivka, and Divača, finally reaching Trieste in 1857.

In 1862, a single-track railway (expanded into double-track in 1944) along the Sava river was built, connecting Zidani Most with Zagreb.

In 1863, the "Carinthian railway" was built along the Drava river, connecting Maribor with Dravograd, Klagenfurt and Villach.

In 1870, a railway along the upper Sava river valley was built, connecting Ljubljana with Kranj, Jesenice and Tarvisio, Italy.

In 1873, a line from Pivka via Illirska Bistrica connected Rijeka, then the most important commercial port in the Hungarian part of the empire.

In 1876, a line from Divača connected Pula, the Austrian naval base, via Prešnica.

In 1906, Bohinj Railway was built, connecting Villach with Jesenice, along the Soča river valley to Gorizia and further to Trieste, with two over 6000 meter tunnels.

After World War II, a single-track electrified line connecting Prešnica with Koper was built in 1967.

In 1999, a single-track line between Murska Sobota and Hodoš was rebuilt, offering a direct connection with the Hungarian railway system.

Left-hand running is used on double-track sections, unlike the remainder of the former Yugoslavian railways.

Due to the Croatian sector of the national railways (as well as the sectors of the other republics of Yugoslavia) choosing the more modern 25 kV system, a voltage break was created in Dobova, which necessitates locomotive switching.

The freight system to Koper, a modern and growing port near Trieste, represents the shortest connection to the Mediterranean for a large portion of the hinterland of Central and Eastern Europe.

In 2010, Slovenske Železnice joined Cargo 10, a joint venture with other railways in the region.

The majority of the EC trains include air-conditioned cars and have catering facilities on board.

The examples include:[5] A noted train of the SŽ was the Casanova linking Ljubljana to Venice in a 4-hour ride, eliminated in April 2007.