), is a private railway company in Greece which operates passenger and freight trains on OSE lines.

[9] On 14 July 2016, the privatisation agency accepted Ferrovie dello Stato Italiane's offer, worth 45 million euros, to buy 100% of TrainOSE.

[10] TrainOSE's shares were completely transferred on 14 September 2017, and is currently a wholly owned subsidiary of Ferrovie dello Stato Italiane.

Seat reservation, bar, and restaurant facilities are available on long-distance express and on Intercity (IC) trains.

Due to the recent railway accident, some routes had limited services or were replaced by buses until the trains resumed again in December 2023.

The rolling stock of the Proastiakos commuter rail services include Class 460 Siemens Desiro five-car electric multiple units (EMU), used on the electrified sections of the Ano Liosia–Athens International Airport, Ano Liosia–Corinth–Kiato and Thessaloniki–Larissa lines; while Stadler GTW 2/6 DMUs and MAN-2000 DMUs are used on the non-electrified section between Piraeus–Athens–Ano Liosia.

In 2024 it was announced that infrastructure would be upgraded so that a high speed rail would connect Budapest to Athens via Belgrade, Skopje and Thessaloniki, linking Greece with Central Europe.

GAIAOSE was appointed administrator of the rolling stock of the Greek State, which leases it to TRAINOSE for a price.

In addition, TRAINOSE leases rolling stock to Rail Cargo Logistics (a member of Goldair), under a special contract.

5 Pendolino trains[20] are expected to arrive in Greece in late 2020 after a delay due to the global pandemic.

[21] In 2022, the Frecciargento ETR 470[22] came into service as the first Italian train, and also hybrid locomotives (both diesel and electric) are planned.

[25] In August 2018, a similar ETR.485 unit transferred to Greece for testing purposes, in anticipation of the ETR 470 fleet's arrival,[26] but because it was not designed for the Greek network, it was decided instead to launch the ETR 470, which were originally expected to come in 2019, with the completion of the electrification and testing of the ETCS.

The remaining units were to gradually arrive and the first route was scheduled to take place on 25 March 2021, according to the statements of Hellenic Train's managing director, Filippos Tsalidis.