Modern relations between the two countries were established in 1908 and are regarded as excellent despite the Axis occupation of Greece by Bulgaria, Italy and Germany during World War II.

[citation needed] While the Bulgarian Orthodox Church was restored in 1872, the Ecumenical Patriarchate, refused to recognize it until much later, in 1945, and especially after the collapse of the Ottoman Empire and the end of the Balkan & World Wars.

After the World War II, the relations between Greece and Bulgaria have been flourishing, and as the Greek President Konstantinos Tsatsos said during the Bulgarian leader Todor Zhivkov's visit to Athens in April 1976, "the old controversies have been forgotten and the hatchet buried forever".

The operation codenamed "Cross" and the plan was that Bulgarian secret agents would set fire on the Ecumenical Patriarchate of Constantinople and make it look like the work of Turks.

In addition, the Bulgarians also planned to boost the effect of its operation against Greece and Turkey by conducting "active measures […] for putting the enemy in a position of delusion."

These communities today are significantly decreased due to the population exchanges between Greece and Bulgaria which were directed under the Treaty of Neuilly in 1919.

[14] In 1900, Greeks were about 80,000 (2% of the Bulgarian population) and despite its small size the minority was prominent in the commercial activities and visible in the cultural life.

However, that number has risen since then, as in 2003–2004, Bulgarians accounted for 9,8% of residence permit holders in Greece, out of which 473 were students and 2,059 were married to EU nationals.

[17] There are numerous publications in Greece for the Bulgarian community, including the bilingual newspaper България днес/Βουλγαρία σήμερα (Bulgaria today).