The Italian Catholic diocese of Ferentino existed until 1986, when it was united into the new diocese of Frosinone-Veroli-Ferentino.
In the time of Emperor Constantine Ferentino had its own bishop; but the first known by name is Bassus, present at Roman synods, 487 and 492-493. St. Redemptus (about 570) is mentioned in the Dialogues of Gregory the Great; and he also refers to a Bishop Boniface.
Other bishops are
Trasmondo Sognino (1150), who died in prison;Ubaldo (1150), legate of Pope Adrian IV to the princes of Christendom in favour of a crusade, later the consecrator of the antipope Victor IV;Giacomo (1276), legate of Pope John XXI to Emperor Michael Palaeologus;Landolfo Rosso (1297), who rendered service to Pope Boniface VIII;Francesco Filippesio (1799), legate of Julius II to the Emperor Maximilian.Albert Longhi (1203 - )...Landolfo Rossi (29 Mar 1298 - 1303 Died)...Giovanni Bonifacio Panella (8 Mar 1392 - 15 May 1395 Appointed, Archbishop of Durrës)Niccolò Vivari (21 May 1395 - 1410 Appointed, Bishop of Spoleto)Antonio Boccabella, O.F.M. (23 Dec 1435 - 24 Jan 1445 Died)Giovanni Tricarico, O.S.A. (12 Feb 1445 - 1453 Died)Antonio Laurenti (28 Sep 1453 - 1498 Died)Pietro de Fenestrosa (4 Jul 1498 - 1499 Died)Francesco Fillipperi (11 Oct 1499 - 1510 Resigned)Tranquillo de Macarazzi (16 Dec 1510 - 1548 Died)Sebastiano Antonio Pighini (4 Jun 1548 - 30 May 1550 Appointed, Archbishop of Manfredonia)Dionisio de Robertis, O.S.M. (30 May 1550 - 30 Mar 1554 Appointed, Archbishop of Manfredonia)Aurelio Tribaldeschi, O.S.Io.Hieros. (30 Apr 1554 - 1584 Died)Silvio Galassi (3 Jun 1585 - 1591 Died)Orazio Ciceroni (31 Jul 1591 - 1603 Died)Fabrizio Campani (7 Apr 1603 - 15 Jun 1605 Died)Dionigi Morelli (5 Aug 1605 - 13 Oct 1612 Died)Ennio Filonardi (bishop) (19 Nov 1612 - 1644 Died)Enea di Cesare Spennazzi (23 May 1644 - 1658 Died)Ottavio Roncioni (8 Jul 1658 - 2 Jul 1676 Died)Giovanni Carlo Antonelli (11 Jan 1677 - 20 Apr 1694 Died)Valeriano Chierichelli (21 Jun 1694 - 14 May 1718 Resigned)Simone Gritti (8 Jun 1718 - 23 Dec 1729 Appointed, Bishop of Acquapendente)Fabrizio Borgia (23 Dec 1729 - 2 Sep 1754 Died)Pietro Paolo Tosi (16 Sep 1754 - 31 Mar 1800 Died)Nicola Buschi (11 Aug 1800 - 23 Sep 1813 Died)Luca Amici (15 Mar 1815 - 8 Feb 1818 Died)Gaudenzio Patrignani, O.F.M. Obs. (25 May 1818 - 15 Feb 1823 Died)Giuseppe-Maria Lais (10 Mar 1823 - 18 Jan 1836 Died)Vincenzo Macioti (1 Feb 1836 - 5 Aug 1840 Died)Giovanni Giuseppe Canali (14 Dec 1840 - 24 Jan 1842 Resigned)Antonio Benedetto Antonucci (22 Jul 1842 - 25 Jul 1844 Appointed, Titular Archbishop of Tarsus)Bernardo-Maria Tirabassi (20 Jan 1845 - 2 Jan 1865 Died)Gesualdo Vitali (27 Mar 1865 - 31 Dec 1879 Died)Pietro Facciotti (27 Jan 1880 - 19 Apr 1897 Resigned)Domenico Bianconi (19 Apr 1897 - 12 Jun 1922 Died)Alessandro Fontana (11 Dec 1922 - 21 Dec 1941 Died)Tommaso Leonetti (14 Apr 1942 - 10 Jul 1962 Appointed, Archbishop of Capua)Costantino Caminada (21 Jul 1962 - 6 Nov 1972 Died)Umberto Florenzani (27 Jan 1973 - 21 Dec 1973 Appointed, Bishop of Anagni)Michele Federici (21 Dec 1973 - 23 Nov 1980 Died)Angelo Cella, M.S.C. (6 Jun 1981 - 30 Sep 1986 Appointed, Bishop of Frosinone-Veroli-Ferentino)