A chronology of key events:
1534 - 1918 - Region is part of the Ottoman Empire.
1917 - Britain seizes Baghdad during First World War.
1920 - League of Nations approves British mandate in Iraq, prompting nationwide revolt.
1921 - Britain appoints Feisal, son of Hussein Bin Ali, the Sherif of Mecca, as king.
1932 - Mandate ends, Iraq becomes independent. Britain retains military bases.
1941 - Britain re-occupies Iraq after pro-Axis coup during Second World War.
1958 - The monarchy is overthrown in a left-wing military coup led by Abd-al-Karim Qasim. Iraq leaves the pro-British Baghdad Pact.
1963 - Prime Minister Qasim is ousted in a coup led by the pan-Arab Baath Party.
1963 - The Baathist government is overthrown, but seizes power again five years later
Baathists in power
1968 - A Baathist led-coup puts Ahmad Hasan al-Bakr in power.
1972 - Iraq nationalises the Iraq Petroleum Company.
1974 - Iraq grants limited autonomy to Kurdish region.
1979 - Saddam Hussein takes over from President Al-Bakr.
1980-1988 - Iran-Iraq war results in stalemate.
1981 June - Israeli air raid destroys Iraqi nuclear reactor at Osirak near Baghdad.
1988 March - Iraq attacks Kurdish town of Halabjah with poison gas, killing thousands.
First US-Iraq war
1990 - Iraq invades and annexes Kuwait, prompting what becomes known as the first Gulf War. A massive US-led military campaign forces Iraq to withdraw in February 1991.
1991 April - Iraq subjected to weapons inspection programme.
1991 Mid-March/early April - Southern Shia and northern Kurdish populations - encouraged by Iraq's defeat in Kuwait - rebel, prompting a brutal crackdown.
1991 April - UN-approved haven established in northern Iraq to protect the Kurds. Iraq ordered to end all military activity in the area.
1992 August - A no-fly zone, which Iraqi planes are not allowed to enter, is set up in southern Iraq.
1995 April - UN allows partial resumption of Iraq's oil exports to buy food and medicine in an oil-for-food programme.
1996 September - US extends northern limit of southern no-fly zone to just south of Baghdad.
1998 October - Iraq ends cooperation with UN Special Commission to Oversee the Destruction of Iraq's Weapons of Mass Destruction.
Operation Desert Fox
1998 December - US and British Operation Desert Fox bombing campaign aims to destroy Iraq's nuclear, chemical and biological weapons programmes.
2002 September - US President George W Bush tells UN Iraq poses "grave and gathering danger".
2002 November - UN weapons inspectors return to Iraq backed by a UN resolution which threatens serious consequences if Iraq is in "material breach" of its terms.
2003 March - US-led invasion topples Saddam Hussein's government, marks start of years of violent conflict with different groups competing for power.
2003 July - US-appointed Governing Council meets for first time. Commander of US forces says his troops face low-intensity guerrilla-style war.
2003 August - Suicide truck bomb wrecks UN headquarters in Baghdad, killing UN envoy Sergio Vieira de Mello.
Car bomb in Najaf kills 125 including Shia leader Ayatollah Mohammed Baqr al-Hakim.
2003 December - Saddam Hussein captured in Tikrit.
2004 March - Suicide bombers attack Shia festival-goers in Karbala and Baghdad, killing 140 people.
2004 April-May - Photographic evidence emerges of abuse of Iraqi prisoners by US troops at Abu Ghreib prison in Baghdad.
Sovereignty and elections
2004 June - US hands sovereignty to interim government headed by Prime Minister Iyad Allawi.
2004 August - Fighting in Najaf between US forces and Shia militia of radical cleric Moqtada Sadr.
2004 November - Major US-led offensive against insurgents in Falluja.
2005 January - Elections for a Transitional National Assembly.
2005 April - Amid escalating violence, parliament selects Kurdish leader Jalal Talabani as president. Ibrahim Jaafari, a Shia, is named as prime minister.
2005 May onwards - Surge in car bombings, bomb explosions and shootings: government puts civilian death toll for May at 672, up from 364 in April.
2005 June - Massoud Barzani is sworn in as regional president of Iraqi Kurdistan.
2005 October - Voters approve a new constitution, which aims to create an Islamic federal democracy.
2005 December - Iraqis vote for the first, full-term government and parliament since the US-led invasion.
2006 February onwards - A bomb attack on an important Shia shrine in Samarra unleashes a wave of sectarian violence in which hundreds of people are killed.
2006 April - Newly re-elected President Talabani asks Shia compromise candidate Nouri al-Maliki to form a new government, ending months of deadlock.
2006 June - Al-Qaeda leader in Iraq, Abu Musab al-Zarqawi, is killed in an air strike.
2006 November - Iraq and Baathist Syria restore diplomatic relations after nearly a quarter century.
2006 December - Saddam Hussein is executed for crimes against humanity.
2007 January - US President Bush announces a new Iraq strategy; thousands more US troops will be dispatched to shore up security in Baghdad.
2007 August - Kurdish and Shia leaders form an alliance to support Prime Minister Maliki's government, but fail to bring in Sunni leaders.
2007 September - Controversy over private security contractors after Blackwater security guards allegedly fire at civilians in Baghdad, killing 17.
2007 December - Britain hands over security of Basra province to Iraqi forces, effectively marking the end of nearly five years of British control of southern Iraq.
2008 March - Prime Minister Maliki orders crackdown on militia in Basra, sparking pitched battles with Moqtada Sadr's Mehdi Army. Hundreds are killed.
2008 September - US forces hand over control of the western province of Anbar - once an insurgent and Al-Qaeda stronghold - to the Iraqi government. It is the first Sunni province to be returned to to the Shia-led government.
Security pact approved
2008 November - Parliament approves a security pact with the United States, under which all US troops are due to leave the country by the end of 2011.
2009 June - US troops withdraw from towns and cities in Iraq, six years after the invasion, having formally handed over security duties to new Iraqi forces.
2010 March - Elections. Parliament approves new government of all major factions in December.
2010 August - Seven years after the US-led invasion, the last US combat brigade leaves Iraq.
2011 January - Radical Shia cleric Moqtada Sadr returns after four years of self-imposed exile in Iran.
US pulls out
2011 December - US completes troop pull-out.
Unity government faces disarray. Arrest warrant issued for vice-president Tariq al-Hashemi, a leading Sunni politician. Sunni bloc boycotts parliament and cabinet.
2012 March - Tight security for Arab League summit in Baghdad. It is the first major summit to be held in Iraq since the fall of Saddam Hussein. A wave of pre-summit attacks kills scores of people.
2012 November - Iraq cancels a $4.2bn deal to buy arms from Russia because of concerns about alleged corruption within the Iraqi government.
2013 April - Sunni insurgency intensifies, with levels of violence matching those of 2008. By July the country is described as being yet again in a state of full-blown sectarian war.
2013 September - Series of bombings hits Kurdistan capital Irbil in the first such attack since 2007. The Islamic State of Iraq group says it was responding to alleged Iraqi Kurdish support for Kurds fighting jihadists in Syria.
2013 October - Government says October is deadliest month since April 2008, with 900 killed. By the year-end the UN estimates the 2013 death toll of civilians as 7,157 - a dramatic increase in the previous year's figure of 3,238.
2014 January - Islamist fighters infiltrate Falluja and Ramadi after months of mounting violence in mainly-Sunni Anbar province. Government forces recapture Ramadi but face entrenched rebels in Falluja.
2014 April - Prime Minister Al-Maliki's coalition wins a plurality at first parliamentary election since 2011 withdrawal of US troops, but falls short of a majority.
2014 June-September - Sunni rebels led by Islamic State of Iraq and the Levant surge out of Anbar Province to seize Iraq's second city of Mosul and other key towns. Tens of thousands flee amid atrocities. Kurdish forces, US and Iran assist government in repelling attacks.
2014 September - Shia politician Haider al-Abad forms a broad-based government including Sunni Arabs and Kurds. Kurdish leadership agrees to put independence referendum on hold.
2014 December - The Iraqi government and the leadership of the Kurdish Region sign a deal on sharing Iraq's oil wealth and military resources, amid hopes that the agreement will help to reunite the country in the face of the common threat represented by Islamic State.
2015 March - Islamic State destroys Assyrian archaeological sites of Nimrud and Hatra.
Offensive against Islamic State
2015-2016 - Government and Islamic State forces fight for control of Tikrit and Anbar Province.
2016 April - Supporters of cleric Moqtada al-Sadr storm parliament building demanding new government to fight corruption and end allocation of government posts along sectarian lines.
2016 November - Parliament recognises the Shia Popular Mobilisation Units (PMU) militia as part of the armed forces with full legal status.
2017 September - Kurds back independence in referendum staged by Kurdish regional government. Baghdad imposes punitive measures.
2017 November - Government forces with Shia and Kurdish allies drive Islamic State out of all but a few redoubts.
Army offensive drives back Kurdish forces in a move aimed at halting the regional government's moves towards an independent Kurdistan.
2018 May - Parliamentary elections. The political bloc of Shia cleric Moqtada al-Sadr wins most votes.
2018 October - Parliament elects veteran Kurdish politician Barham Salih as president. He appoints Adel Abdul Mahdi as prime minister, with the support of the Shia majority of MPs.
2019 September-November - At least 400 people die in protests against unemployment and corruption in cities including the capital Baghdad, prompting Adel Abdul Mahdi to tender his resignation.