He fled Iraq in the late 1970s to Iran where SCIRI was founded in 1982. It was created to oppose Saddam Hussein's rule, and aided the Iranian army in the eight-year Iran-Iraq war.
Al-Hakim led the Badr Brigades military wing, which had a major role in the 1991 Shia uprising against the Iraqi government.
He belongs to the prominent religious al-Hakim family based in al-Najaf. Reports suggest that the family is descendant from Persian origin.
Abd Al-Aziz al-Hakim returned to Iraq after the US-led invasion in 2003, and was selected as a Shia member in the US-appointed Iraqi Governing Council (IGC).
His brother, Muhammad Baqir al-Hakim, was assassinated in al-Najaf on 29 August 2003, and he succeeded him as chairman of SCIRI.
SCIRI became an influencing power in Iraq's politics after the occupation. It pushed hard to secure an Iranian-style government in Iraq.
However, al-Hakim was not included in the Iraqi interim government that replaced the US-appointed Iraq Governing Council (IGC) and eventually returned to Iran.