The Diocese of Montalcino (Latin: Dioecesis Ilcinensis) was a Roman Catholic diocese located in the town of Montalcino to the west of Pienza, close to the Crete Senesi in Val d'Orcia in Tuscany, Italy. In 1986, it was suppressed and united with the Diocese of Colle di Val d'Elsa and the Archdiocese of Siena to form the Archdiocese of Siena-Colle di Val d'Elsa-Montalcino.
1462 August 13: Established as the Diocese of Montalcino from the Diocese of Arezzo, the Diocese of Chiusi, and the Diocese of Grosseto 1772 June 15: Gained territory from the Diocese of Chiusi and the Diocese of Pienza 1986 September 30: Suppressed to the Archdiocese of Siena-Colle di Val d'Elsa-Montalcino
Erected: 13 August 1462
Latin Name: Ilcinensis
Immediately Subject to the Holy See
Giovanni Chinugi (7 Oct 1462 - 30 Sep 1470 Died)
Tommaso della Testa Piccolomini (26 Oct 1470 - 1482 Died)
Agostino Patrizi de Piccolomini (19 Jan 1484 - 1495 Died)
Francesco Todeschini-Piccolomini (31 Oct 1495 - Mar 1498 Resigned)
Girolamo Piccolomini (senior) (14 Mar 1498 - 1510 Resigned)
Girolamo Piccolomini (junior) (9 Dec 1510 - 20 Nov 1528 Resigned)
Alessandro Piccolomini (20 Nov 1528 - 1554 Resigned)
Francesco Maria Piccolomini (20 Apr 1554 - 1599 Died)
Camillo Borghese (7 Jan 1600 - 24 Jan 1607 Appointed, Archbishop of Siena)
Mario Cossa (2 Apr 1607 - 1618 Died)
Ippolito Borghese, O.S.B. (26 Mar 1618 - 1 Sep 1636 Appointed, Bishop of Pienza)
Scipione Tancredi (2 Mar 1637 - 13 Apr 1641 Died)
Alessandro Sergardi (21 Oct 1641 - Apr 1649 Died)
Antonio Bichi (8 Dec 1652 Ordained Bishop - 6 Mar 1656 Appointed, Bishop of Osimo)
Lorenzo Martinozzi, O.S.B. (16 Oct 1656 - Aug 1663 Died)
Fabio de Vecchi (14 Jan 1664 - Aug 1688 Resigned)
Romualdo Tancredi, O.S.B. (9 Aug 1688 - Dec 1694 Died)
Giuseppe Maria Borgognini (28 Nov 1695 - Nov 1726 Died)
Bernardino Ciani, O.S.A. (30 Jul 1727 - 9 Aug 1767 Died)
Domenico Andrea Vegni (14 Dec 1767 - 8 Nov 1773 Died)
Giuseppe Bernardino Pecci, O.S.B. (27 Jun 1774 - 1809 Died)
Giacinto Pippi (15 Mar 1815 - 12 Jul 1824 Appointed, Bishop of Chiusi e Pienza)
Giovanni Bindi Sergardi (20 Dec 1824 - 18 Nov 1843 Died)
Paolo Giovanni Bertolozzi (7 Jan 1850 - 27 Jan 1867 Died)
Raffaele Pucci-Sisti (23 Feb 1872 - 30 May 1879 Died)
Donnino Donnini (19 Sep 1879 - 14 Dec 1891 Appointed, Bishop of Arezzo)
Amilcare Tonietti (12 Jun 1893 - 25 Sep 1899 Resigned)
Iader Bertini (18 Sep 1899 - 27 Sep 1908 Died)
Alfredo del Tomba (29 Apr 1909 - 10 Jul 1937 Resigned)
Ireneo Enrico Chelucci (22 Jul 1938 - 8 Jun 1970 Died)
Ismaele Mario Castellano, O.P. (19 Jan 1978 - 30 Sep 1986 Appointed, Archbishop of Siena-Colle di Val d'Elsa-Montalcino)
1986 Sep 30: Suppressed to the Archdiocese of Siena-Colle di Val d'Elsa-Montalcino
