A chronology of key events:
Introduction of constitution which limits the royal absolutism of past dynasties that ruled Persia over the previous five centuries.
1921 22 February - Military commander Reza Khan seizes power.
1923 - Reza Khan becomes prime minister.
1925 12 December - Parliament, in a constituent assembly, vote to vest the crown of Iran in Reza Shah Pahlavi.
1926 25 April - The coronation takes place and the Pahlavi era begins. Mohammad Reza, the Shah's eldest son, is proclaimed Crown Prince.
1935 - Formerly known as Persia, Iran is adopted as the country's official name.
1941 - The Shah's pro-Axis allegiance in World War II leads to the Anglo-Russian occupation of Iran and the deposition of the Shah in favour of his son, Mohammad Reza Pahlavi.
1950 - Ali Razmara becomes prime minister and is assassinated less than nine months later. He is succeeded by the nationalist, Mohammad Mossadeq.
1951 April - Parliament votes to nationalise the oil industry. The Anglo-Iranian Oil Company is unable to continue operations and as a result Britain boycotts the purchase of Iranian oil. A power struggle between the Shah and Mossadeq ensues.
1953 22 August - With the help of western backing, mainly due to oil interests in the country, the Shah overthrows Mossadeq in a coup d'etat staged by General Fazlollah Zahedi.
Campaign to modernise
1963 26 January - The Shah embarks on a campaign to modernise and westernise the country. He launches the 'White Revolution', a programme of land reform and social and economic modernization. During the late 1960's the Shah became increasingly dependent on the Secret Police (SAVAK) in controlling those opposition movements critical of his reforms.
1978 September - The Shah's policies alienate the clergy and his authoritarian rule leads to riots, strikes and mass demonstrations. Martial law is imposed.
Shah exiled, Khomeini returns
1979 16 January - As the political situation deteriorates, the Shah and his family are forced into exile.
1979 1 February - The Islamic fundamentalist, Ayatollah Ruhollah Khomeini, returns to Iran following 14 years of exile in Iraq and France for opposing the regime.
1979 1 April - The Islamic Republic of Iran is proclaimed following a referendum.
1979 4 November - Islamic militants take 52 Americans hostage inside the US embassy in Tehran. They demand the extradition of the Shah, in the US at the time for medical treatment, to face trial in Iran.
1980 25 January - Abolhasan Bani-Sadr is elected the first President of the Islamic Republic. His government begins work on a major nationalization programme.
1980 27 July - The exiled Shah dies of cancer in Egypt.
1980 22 September - Iraq invades Iran following border skirmishes and a dispute over the Shatt al-Arab waterway. This marks the beginning of a war that will last eight years.
1981 20 January - The American hostages are released ending 444 days in captivity.
1981 22 June - Bani-Sadr is dismissed, he later flees to France.
1985 - After the US and Soviet Union halted arms supplies, the US attempted to win the release of hostages in Lebanon by offering secret arms deals, this would later become known as the Iran-Contra affair.
1988 3 July - 290 passengers and the crew of an Iran Air Airbus are mistakenly shot down by the USS Vincennes.
1988 20 July - Iran accepts a ceasefire agreement with Iraq following negotiations in Geneva under the aegis of the UN.
1989 14 February - Ayatollah Khomeini issues a religious edict (fatwa) ordering Muslims to kill British author, Salman Rushdie, for his novel, 'The Satanic Verses', considered blasphemous to Islam.
1989 3 June - Ayatollah Khomeini dies. On 4 June, President Khamene'i is appointed as new supreme leader.
1989 17 August - Ali Akbar Hashemi-Rafsanjani is sworn in as the new president.
1989 3 November - The US releases 567 million dollars of frozen Iranian assets.
Major earthquake kills thousands
1990 21 June - A major earthquake strikes Iran, killing approximately 40,000 people.
1990 - Iran remains neutral following Iraq's invasion of Kuwait, denouncing both Baghdad's conquest of Kuwait and any long-term presence of US forces in the region.
1990 11 September - Iran and Iraq resume diplomatic relations.
US imposes sanctions
- The US imposes oil and trade sanctions against Iran for alleged sponsorship of 'terrorism', seeking to acquire nuclear arms and hostility to the Middle East process. Iran denies the charges.
1997 23 May - Mohammad Khatami wins the presidential election by a landslide, with 70% of the vote beating the conservative ruling elite.
1998 September - Iran deploys thousands of troops on its border with Afghanistan after the Taleban admits killing eight Iranian diplomats and a journalist in Mazar-e Sharif.
1999 July - Pro-democracy students at Tehran University hold a demonstration following the closure of the reformist newspaper 'Salam'. Clashes with the security forces lead to six days of rioting and the arrest of over 1,000 students.
2000 February - Liberals and supporters of Khatami win 170 of the 290 seats in the Majlis elections held February, thus gaining control of parliament previously dominated by the conservatives since the 1979 Islamic revolution. Hard-liners win only 44 seats. An additional 65 seats will be decided in run-offs.
2000 April - The judiciary, following the adoption of a new press law, bans the publication of 16 reformist newspapers.
2000 May - Inauguration of the Sixth parliament.
2000 August - Senior clerics issue a religious decree, or fatwa, allowing women to lead religious congregations of women worshippers.
2001 April - Iran and Saudi Arabia sign major security accord to combat terrorism, drug trafficking and organised crime.
Khatami's second term
2001 June - President Khatami re-elected for a second term after winning just under 77% of the vote.
2001 August - President Mohammad Khatami sworn in for his second term in office.
2002 January - US President George Bush describes Iraq, Iran and North Korea as an "axis of evil", warning of the proliferation of long-range missiles being developed in these countries. The speech causes outrage in Iran and is condemned by reformists and conservatives alike.
2002 September - Russian technicians begin construction of Iran's first nuclear reactor at Bushehr despite strong objections from US.
2003 June - Thousands attend student-led protests in Tehran against clerical establishment.
2003 September - UN nuclear watchdog, IAEA, gives Tehran weeks to prove it is not pursuing an atomic weapons programme.
2003 October - Shirin Ebadi becomes Iran's first Nobel Peace Prize winner; lawyer and human rights campaigner became Iran's first female judge in 1975 but was forced to resign after 1979 revolution.
2003 November - Iran says it is suspending its uranium enrichment programme and will allow tougher UN inspections of its nuclear facilities. IAEA report concludes there is no evidence of a weapons programme.
2003 December - 40,000 people are killed in an earthquake in south-east Iran; the city of Bam is devastated.
2004 February - Conservatives gain control of parliament in controversial elections; their win is consolidated in a second round of voting in May. Thousands of reformist candidates were disqualified by the hardline Council of Guardians ahead the polls.