According to the Treaty of Bucharest concluded after the Bulgarian defeat, Bulgaria had to hand over Southern Dobruja region to Romania.

In the cold war, both countries became communist states under the influence of the Soviet Union, but Romania formally left the sphere in 1964.

Romanian-Bulgarian relations are developing "very intensively" because of EU accession, since Romania and Bulgaria both joined the European Union in 2007.

A diplomatic row broke out in August 2019 between Bulgaria and Romania over the African swine fever (ASF).

[1] The Bulgarian Prime Minister, Boyko Borisov, accused Romanian tourists of bringing the ASF disease and helping to spread it.

"[1] The Romanian foreign ministry replied that it was disappointed by Borisov's words and that Romanian tourists boost Bulgaria's GDP: "Beyond the technical arguments that will be offered by the National Veterinary Health and Food Safety Authority to respond to the unfortunate statements of the prime minister of Bulgaria, Boyko Borisov, we are surprised and disappointed by the way the Bulgarian prime minister has referred to Romanian tourists, who make a substantial contribution to the GDP of Bulgaria".