(Click on the column title to sort by that column)
| # | Catholics | Population | Percent Catholic | Diocese | Year | Source |
|---|---|---|---|---|---|---|
| 1 | 441,449 | 4,024,454 | 10.97% | Alba Iulia (Archdiocese) | 2004 | ap2005 |
| 2 | 350,000 | Fagaras e Alba Iulia (Romanian) (Archdiocese) | 2004 | ap2005 | ||
| 3 | 258,913 | 4,301,490 | 6.02% | Iasi | 2004 | ap2005 |
| 4 | 168,000 | 1,520,000 | 11.05% | Timisoara | 2004 | ap2005 |
| 5 | 128,490 | Maramures (Romanian) | 2004 | ap2005 | ||
| 6 | 106,827 | 1,014,420 | 10.53% | Oradea Mare {Gran Varadino, Nagyvárad} | 2004 | ap2005 |
| 7 | 102,000 | Oradea Mare {Gran Varadino} (Romanian) | 2004 | ap2005 | ||
| 8 | 96,427 | Lugoj (Romanian) | 2004 | ap2005 | ||
| 9 | 96,200 | 10,000,000 | .96% | Bucarest {Bucuresti} (Archdiocese) | 2004 | ap2005 |
| 10 | 70,000 | 850,000 | 8.24% | Satu Mare {Szatmár} | 2004 | ap2005 |
| 11 | 60,000 | Cluj-Gherla (Romanian) | 2004 | ap2005 | ||
| 12 | 515 | Romania, Faithful of Eastern Rite (Armenian) (Ordinariate) | 2004 | ap2005 |
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