The former Italian Catholic Diocese of Chiusi-Pienza, in Tuscany, existed until 1986. In that year it was united into the Diocese of Montepulciano-Chiusi-Pienza. It was a suffragan of the archdiocese of Siena.
Catacombs are found at Chiusi. The martyrdom of the deacon Irenaeus and the virgin Mustiola probably took place under Valerian. The first known bishop was Florentius, present in 465 at the Roman synod under Pope Hilary. Ammiato Abbey was built by Ratchis, King of the Lombards, and afterwards rose to great power and influence.
Bishop Francesco degli Atti (1348) was a famous canonist. Chiusi formerly boasted of a famous relic, the betrothal ring of the Blessed Virgin, which was taken to Perugia about 1449 by an Augustinian friar; in consequence of this a war broke out between them, in which Perugia was victorious and remained in possession of the ring.
The Diocese of Chiusi was at first immediately subject to the Holy See, but was made a suffragan of Siena by Pope Pius II. In 1773 Pope Clement XIV added to it the Diocese of Pienza.
Erected: 3rd Century
Latin Name: Clusinus
Metropolitan: Archdiocese of Siena
Matteo Orsini, O.P. (12 Jan 1317 – 15 Jun 1322 Died)
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Alessio de Cesari (7 Jan 1437 – 5 Mar 1462 Appointed, Archbishop of Benevento)
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Bonifacio di Castel Lotario (8 Feb 1503 – 1504 Died)
Niccolò Bonafede (20 Jun 1504 – 1533 Died)
Bartolomeo Ferratini (14 Jan 1534 – Jun 1534 Died)
Gregorio Magalotti (20 Aug 1534 – Sep 1537 Died)
Giorgio Andreasi (20 Mar 1538 – 2 Apr 1544 Appointed, Bishop of Reggio Emilia)
Giovanni Ricci (20 Feb 1545 – 19 Nov 1554 Resigned)
Figliuccio de Figliucci (19 Nov 1554 – 1558 Died)
Salvatore Pacini (24 Aug 1558 – 1581 Died)
Masseo Bardi, O.F.M. (29 May 1581 – 1597 Died)
Ludovico Martelli ( 1597 – 1601 Died)
Fausto Malari (Molari, Mellari) (22 Apr 1602 – 1608 Died)
Orazio Spannocchi (12 Jan 1609 – 5 Sep 1620 Died)
Alfonso Petrucci (16 Nov 1620 – Mar 1633 Died)
Giovanni Battista Piccolomini (20 Jun 1633 – 14 Jul 1637 Died)
Ippolito Campioni, O.S.B. (14 Dec 1637 – 27 Jan 1647 Died)
Carlo de' Vecchi (2 Mar 1648 – 12 Mar 1657 Resigned)
Alessandro Piccolomini (12 Mar 1657 – 6 Nov 1661 Died)
Marco Antonio Marescotti (11 Feb 1664 – 8 Dec 1681 Died)
Lucio Borghesi (25 May 1682 – 31 Jul 1705 Died)
Gaetano Maria Bargagli, O.S.B. (22 Feb 1706 – 30 Jun 1729 Died)
Giovanni Battista Tarugi (23 Dec 1729 – 14 Sep 1735 Died)
Pio Magnoni (9 Jul 1736 – 4 Sep 1747 Appointed, Bishop of Montepulciano)
Giustino Girolamo Bagnesi, O.S.B. (15 Jul 1748 – Jan 1775 Died)
Giuseppe Pannilini (13 Nov 1775 – 12 Aug 1823 Died)
United: 15 June 1772 with the Diocese of Pienza
Immediately Subject to the Holy See
Giacinto Pippi (12 Jul 1824 – 30 Dec 1839 Died)
Giovanni Battista Ciofi (27 Jan 1843 – 25 Mar 1870 Died)
Raffaele Bianchi (29 Jul 1872 – 30 Dec 1889 Resigned)
Giacomo Bellucci (30 Dec 1889 – 19 Feb 1917 Died)
Giuseppe Conti (22 Mar 1917 – 24 Apr 1941 Died)
Carlo Baldini, O.M.D. (31 Jul 1941 – 2 Jan 1970 Died)
Alberto Giglioli (7 Oct 1975 – 30 Sep 1986 Appointed, Bishop of Montepulciano-Chiusi-Pienza)
30 September 1986: United with the Diocese of Montepulciano to form the Diocese of Montepulciano-Chiusi-Pienza
