Currently the Hellenic Railways Organisation (OSE) owns and maintains the following lines:
Major rail network
- The main line from Piraeus to Thessaloniki (with its branches at Inoi-Chalkis and Lianokladi-Lamia-Stylis). The sections between Athens-Tithorea and Domokos-Thessaloniki have been extensively modernised and feature an electrified double track.
- The main line from Athens to Corinth–Kiato (Line is mainly used by the Proastiakos commuter rail service).
- The electrified single track line from Thessaloniki to Idomeni.
Minor rail network
- The standard gauge single track line from Platy (branching off from the Athens-Thessaloniki mainline) to Florina and Kozani, forming the Kozani-Amyntaio railway line.
- The standard gauge single track line Thessaloniki to Alexandroupolis and Ormenio, with its branch to Promachon at the Greek-Bulgarian borders.
- The standard gauge lines of Thessaly (Kalambaka and Volos branches), as part of the Thessaly rail network .
Peloponnese metre gauge network
- Metre gauge line from Athens to Patras (although in use after Kiato).
- Metre gauge line from Patras to Pyrgos.
- Metre gauge line from Pyrgos to Olympia.
- Metre gauge line from Pyrgos to Katakolo.
- Metre gauge line from Pyrgos to Zevgolatio (via Kalo Nero),
- Metre gauge line from Corinth to Kalamata (via Argos, Tripoli and Zevgolatio),
- Metre gauge line from Argos to Naufplion,
- Metre gauge line from Kalo Nero to Kyparissia,
- Metre gauge line from Kalamata to Messene.
Tourist rail network
- The narrow gauge rack railway line from Diakopto to Kalavryta (the Diakofto–Kalavryta Railway)
- The seasonal, narrow gauge line from Ano Lechonia to Milies (the Pelion railway)