The heron was found dead a week ago in an uninhabited area near Romania's border with Moldova. The positive results for the deadly H5N1 virus were confirmed by tests in a laboratory in Britain.
Earlier this month, Romania detected the H5N1 virus in two villages in the Danube Delta, in the southeast of the country. More than 21,000 domestic birds in the two villages were killed and the villages were placed under quarantine.
The lethal form of bird flu has killed at least 60 people in Asia since 2003.In Europe, the H5N1 strain has also been found in birds in Turkey, Russia, and in a South American parrot held in quarantine in Britain.