Blaj (Romanian pronunciation: [blaʒ]; archaically spelled as Blaș; Hungarian: Balázsfalva; German: Blasendorf; Transylvanian Saxon: Blußendref) is a city in Alba County, Transylvania, Romania.

The city administers eight villages: Deleni-Obârșie (Obursatanya), Flitești, Izvoarele (until 1960 Ciufud; Csufud), Mănărade (Monora), Petrisat (Magyarpéterfalva), Spătac (Szászpatak), Tiur (Tűr), and Veza (Véza).

In 1848, Câmpia Libertății in Blaj was where over 40,000 Romanians met to protest Transylvania becoming a part of Hungary, holding that the lands would be stolen from them.

In terms of religious affiliation, 14,784 (71.19%) were Romanian Orthodox, 2,732 (13.24%) Greek-Catholic, 744 (3.58%) Roman Catholic, 985 Reformed Church, 408 Baptist, and 220 Pentecostal.

Other sights worth visiting include the Metropolitan Palace, the Holy Trinity Cathedral, the "Buna Vestire" Monastery, the Greeks' Church, the "Liberty Field", and Avram Iancu's oak.