|Duchess of Parma|
|Consort||19 August 1545 – 10 September 1547|
|Spouse||Pier Luigi Farnese|
Vittoria, Duchess of Urbino
Ottavio, Duke of Parma
Orazio, Duke of Castro
Rome, Papal States
Palazzo Farnese, Duchy of Parma
Born in Rome, she was the daughter of Lodovico Orsini and Giulia Conti. In 1513 an engagement contract between Orsini and Pier Luigi Farnese was drawn up, and in 1519 the wedding celebrated at Valentano. Her husband was the illegitimate son of Pope Paul III and Silvia Ruffino. The couple had five children three of which would have further progeny. Despite a loveless marriage, Gerolama remained a faithful, devoted wife, tolerating Pier Luigi's excesses, brutality, and extravagances with dignity.
When Cardinal Alessandro Farnese became Pope Paul III in 1534 he made his son Pier Luigi captain-general of the Church and in 1537 duke of Castro and finally in 1545 Duke of Parma and Piacenza. He was murdered in 1547, and Gerolama outlived him by 43 years, dying at the Palazzo Farnese Piacenza in 1590. She was buried at the Farnese crypt at the Sanctuary of Santa Maria della Steccata, Parma.
- Alessandro Farnese (5 October 1520 – 2 March 1589) never married.
- Vittoria Farnese (1521 – 13 September 1602) married Guidobaldo della Rovere, Duke of Urbino and had issue.
- Ottavio Farnese, Duke of Parma (9 October 1524 – 18 September 1586) married Margaret of Parma and had issue.
- Orazio Farnese, Duke of Castro (died 18 July 1558) married Diane de France no issue.
- Ranuccio Farnese (11 August 1530 – 1556) died unmarried.
Titles, styles, honours and arms
Titles and styles from marriage
- 31 October 1537 – 16 September 1545 Her Highness the Duchess of Castro
- 16 September 1545 – 10 September 1547 Her Highness the Duchess of Parma
- 10 September 1547 – 1590 Her Highness the Dowager Duchess of Parma
- van de Pas, Leo. "Gerolama Orsini". Genealogics.org. Retrieved 2010-10-25.