It reaches Ormenio, the current terminus of all passenger services, shortly before crossing the Bulgarian border and continuing to Svilengrad, where it joins the railway from Sofia to Istanbul.

The section between Alexandroupolis (formerly Dedeagatch) and Svilengrad was opened in 1873[5] by the Chemins de fer Orientaux (CO) when the entire Thrace was part of the Ottoman Empire.

as a subsidiary company to undertake the completion of the Alexandroupolis-Svilengrad section of the former Eastern Railways, its headquarters was located in Paris.

[8] Overall, this line was 165 km[9] long route from the Aegean Sea port city Alexandroupolis to Ormenio the last station in Greece before entering Bulgaria.

Likewise, when Greek State Railways (SEK) took over from the CFFH, they kept the operating right through Edirne Karaagaç.

[11] These rights survived until 1971 when TCDD inaugurated its own line from Pehlivanköy to Edirne & Svilengrad fully on Turkish territory.

At the same time, in 1971, SEK designed and constructed a 9 km (5.6 mi) direct connection between Nea Vyssa and Marasia within the Greek borders, thus avoiding Turkish territory and bypassing Karaağaç and with a new intermediate station at Kastanies.

During the Greek Civil War until 1949, the trains operated only by daylight and were supplemented with empty freight cars in front of the locomotive and armed with escort to protect them from mines.

The project at the Pythion-Ormenio section envisions upgrading the existing line and the construction of a second one, as well as the installation of electrification signalling (ETCS Level 1) along the entire stretch, with the aim of improving freight transport with Bulgaria and Turkey.

[16][17] Major overhaul including electrification and signaling upgrades was proposed in 2021 as one of the six railway projects of the Greek authorities submitted before the EU.