Abdel Aziz Ar-Rantissi was born in 1947 in Yubna, near Jaffa (in today’s Israel). At the age of one, his family moved to the Gaza Strip, where he completed his secondary school education. He was then admitted as a student to the Faculty of Medicine at Alexandria University, from which he graduated in 1972 with a degree in paediatric medicine. While studying in Egypt, Rantissi was considerably influenced by the philosophy of the Muslim Brotherhood, which had been outlawed in the country.

In 1976, he returned to Gaza and became part of the Muslim Brotherhood movement. He also worked as a resident physician at Nasser Hospital (the main medical centre in Khan Yunis). He occupied several posts in public works such as a member in the administrative board of the Islamic Complex, Arab Medical Society in Gaza, and the Palestinian Red Crescent Society. Rantissi joined the Faculty of Science at the Islamic University of Gaza when it opened in 1978 and also became Chief Paediatrician in the Government Hospital in Khan Yunis.

He rose to prominence with Hamas in the course of the 1st Intifada, during which he was arrested several times by Israel, including for a period of more than 2 years, from March 1988 to September 1990. In 1992, he was deported to Lebanon, alongside with 416 other Islamic militants from Hamas and Islamic Jihad. Rantissi emerged as general spokesman of those expelled to southern Lebanon. Following his return to Gaza in 1993, he was repeatedly detained by the Palestinian National Authority (PNA), for his virulent criticisms of the PNA and of Yasser Arafat.

After the return of Sheikh Ahmad Yassin to the Gaza Strip in 1997, Yassin, the spiritual leader of Hamas, together with senior operatives including Rantissi, reorganized the Hamas leadership in the Gaza Strip in order to reinstate its activities. In mid-1999, following his release from a PNA prison, Rantissi returned to his position as « right hand » to Yassin. During talks between Hamas leadership in Gaza Strip and abroad and the PA regarding ceasefire with Israel, Rantissi voiced his harsh opposition to any cease-fire and cessation of terrorist attacks inside Israel. Abd al-Aziz Ar-Rantissi replaced Salah Shehadeh and Ibrahim Maqadma, after they were assassinated by Israel, as the contact person between the military wing and the political wing of Hamas.

Israel unsuccessfully attempted to assassinate Rantissi on the 10th of June 2003, following a Hamas attack, in which 4 Israeli soldiers were killed at Erez checkpoint in the Gaza strip. Upon the assassination of Sheikh Ahmad Yassin on the 22nd of March 2004, Rantissi took over the leadership of the militant Islamic movement Hamas in the Gaza Strip, while Khaled Meshaal, the Hamas politburo chief living in exile in Syria, remains the group’s overall leader. A few weeks later, on the 15th of April, he was assassinated by Israeli forces in an attempt to weaken Hamas. He had already been openly threatened on different occasions since he had assumed his new post. The assassination was widely condemned, and Javier Solana, the European Union High Representative for foreign policy, declared that such an act would not facilitate a positive issue to the peace process in the Middle East.

Rantissi had become the group’s most visible figure since the beginning of the 2nd Intifada. He was one of the most forceful spokesmen against compromise with Israel, given that he did not recognize Israel’s right to exist and had consistently opposed joining other factions in declaring a cease-fire.