| Dioceses | Catholics | Total Population | Statistic Year |
| Ha Noi | 340,000 | 8,850,000 | 2010 |
| Bac Ninh | 124,200 | 8,000,000 | 2010 |
| Bui Chu | 384,453 | 1,825,771 | 2010 |
| Hai Phong | 134,846 | 5,150,000 | 2010 |
| Hung Hoa | 227,647 | 6,963,632 | 2010 |
| Lang Son-Cao Bang | 5,269 | 1,767,308 | 2010 |
| Phat Diem | 160,558 | 995,017 | 2010 |
| Thai Binh | 135,178 | 3,250,000 | 2010 |
| Thanh Hoa | 138,839 | 3,800,000 | 2010 |
| Vinh | 497,806 | 5,383,000 | 2010 |
| Hue | 68,910 | 2,320,000 | 2010 |
| Ban Me Thuot | 397,211 | 2,730,956 | 2010 |
| Da Nang | 69,914 | 2,682,100 | 2010 |
| Kontum | 260,875 | 1,707,451 | 2010 |
| Nha Trang | 200,400 | 1,730,828 | 2010 |
| Qui Nhon | 69,512 | 3,785,600 | 2010 |
| Ho Chi Minh | 677,820 | 6,825,286 | 2010 |
| Ba Ria | 242,243 | 1,012,966 | 2010 |
| Can Tho | 196,932 | - | 2010 |
| Đa Lat | 349,385 | 9,764,800 | 2010 |
| Long Xuyen | 217,526 | 5,353,857 | 2010 |
| My Tho | 120,300 | 4,776,036 | 2010 |
| Phan Thiet | 166,803 | 1,169,450 | 2010 |
| Phu Cuong | 131,345 | 2,888,328 | 2010 |
| Vinh Long | 196,155 | 3,976,522 | 2010 |
| Xuan Loc | 921,489 | 2,602,913 | 2013** |