The Diocese of Iba (Lat: Dioecesis Ibanae) is a Latin Church ecclesiastical jurisdiction or diocese of the Catholic Church in the Philippines that comprises the province of Zambales and City of Olongapo.

On 12 June 1955, a territorial prelature was erected from territory in the dioceses of San Fernando, Pampanga, and of Diocese of Lingayen-Dagupan and was elevated as the Diocese of Iba on 15 November 1982. The diocese is part of the Ecclesiastical Province of San Fernando, Pampanga.

On 17 February 2018, Bartolome G. Santos Jr., the vicar general of the Diocese of Malolos and rector of the National Shrine of Our Lady of Fatima was designated as the new bishop replacing Florentino G. Lavarias who vacated the post after his installation as the Archbishop of the Archdiocese of San Fernando, Pampanga. The latter also served as a co-consecrator for Bishop Santos's ordination alongside Manila Archbishop Cardinal Luis Antonio G. Tagle who served as principal consecrator and the late Malolos Bishop Jose F. Oliveros, and as installing prelate during his installation.

The transfixed flaming heart is the symbol of Augustine of Hippo, Doctor of the Church, who is the titular of the cathedral. The bezants represent the great wealth found in the Zambales mountains which cover the territory of the diocese.

• 
  The original coat of arms as designed by Bishop Mariano Madriaga

Bishop		Period in Office	Coat of Arms
1.	Henry Byrne	August 20, 1956 - July 16, 1983 Resigned
2.	Paciano B. Aniceto	October 20, 1983 - March 14, 1989 appointed Archbishop of San Fernando
3.	Deogracias S. Iñiguez, Jr.	December 27, 1989 - August 22, 2003 appointed Bishop of Kalookan
4.	Florentino G. Lavarias	September 1, 2004 - October 27, 2014 appointed Archbishop of San Fernando
5.	Bartolome G. Santos	May 25, 2018 - present

• Daniel O. Presto, 6th Bishop of the Diocese of San Fernando de La Union.
• Teodoro Bacani, Bishop Emeritus of the Diocese of Novaliches.

• Catholic Church in the Philippines
• List of Catholic dioceses in the Philippines

• Media related to Roman Catholic Diocese of Iba at Wikimedia Commons
• Diocese of Iba page on the Catholic Bishops Conference of the Philippines website
• Diocese of Iba Facebook Page

15°19′34″N 119°58′47″E / 15.3262°N 119.9798°E / 15.3262; 119.9798