- After months of protests, on January 16, 1979, the US-backed shah, Mohammad Reza Pahlavi, leaves the country.
PARIS: Iran goes to the polls next week to choose a new president, as the second term of moderate Hassan Rouhani comes to an end.
Here are key events that have marked the country since the 1979 revolution that overthrew the US-backed monarchy and established an Islamic republic.
1979: Islamic republic
After months of protests, on January 16, 1979, the US-backed shah, Mohammad Reza Pahlavi, leaves the country.
Revolutionary leader Ayatollah Ruhollah Khomeini makes a triumphant return from exile on February 1.
Ten days later the shah's government falls, with public radio declaring "the end of 2,500 years of despotism".
An Islamic republic is proclaimed on April 1.
US hostage crisis
Radical students take 52 Americans hostage at the US embassy in Tehran on November 4, 1979, to protest the ex-shah's admission to hospital in the US.
Washington severs diplomatic relations in 1980. The hostages are freed on January 21, 1981, after 444 days in captivity.
1980-88: Iran-Iraq war
Iraq attacks Iran on September 22 after its president, Saddam Hussein, tears up a 1975 treaty on the strategic Shatt al-Arab waterway.
It triggers an eight-year war that is widely estimated to have cost hundreds of thousands of lives on both sides. It ends on August 20, 1988 with a UN-brokered ceasefire.
1989: Khamenei takes over
Khomeini dies on June 3, 1989 and Ayatollah Ali Khamenei, president since 1981, becomes supreme leader.
Moderate conservative Akbar Hashemi Rafsanjani is elected president.
Re-elected in 1993, he orchestrates a relative opening up of the government and post-war reconstruction.
Rafsanjani's reformist successor, Mohammad Khatami, runs up against conservative opposition during his two terms from 1997 to 2005.
In 1999 the government faces the biggest protests since 1979, with students who back Khatami clashing with police.
2002: 'Axis of evil'
US president George W. Bush names Iran as part of an anti-American "axis of evil" with Iraq and North Korea, accusing it of supporting terrorism.
2005: Ahmadinejad era
Hardliner Mahmoud Ahmadinejad is elected president in June.
During his tenure, Iran resumes uranium enrichment, alarming the West, which suspects it of wanting to produce a nuclear weapon. Iran has consistently rejected that claim.
A crackdown on nationwide protests against his disputed re-election in 2009 hobbles the reformist movement.
2015: Nuclear deal
The election of moderate cleric Rouhani as president in 2013 marks a warming of relations with Washington and the rest of the world.
An accord on Iran's nuclear programme is reached with world powers, including the US, on July 14, 2015, after 21 months of negotiations.
It gives Tehran relief from crippling economic sanctions in exchange for limits on its nuclear programme.
2016: Saudi standoff
In January Iran's regional rival Saudi Arabia and its allies cut or scale back relations, following a crisis prompted by the Sunni kingdom's execution of a prominent Shiite cleric.
2018: US quits nuclear deal
US president Donald Trump on May 8 abandons the nuclear deal and begins reimposing unilateral sanctions on Iran.
A year later Tehran begins gradually stepping back from its own commitments.
2020: Top commander killed
On January 3 a US strike kills top Iranian commander Qasem Soleimani in Iraq, prompting fears of direct confrontation. Five days later, Iran launches a volley of missiles at US troops stationed in Iraq.
2021: Gulf, Israel tensions
The Revolutionary Guards in January seize a South Korean-flagged tanker in the Gulf amid a dispute over billions in frozen oil funds, the latest in a series of incidents there, with the ship released in April.
Also in April, Iran claims Israel is behind an explosion at its Natanz uranium enrichment plant.
In a surprise move in May, the conservative-dominated Guardian Council disqualifies key establishment figure Ali Larijani from the June 18 presidential election.
It approves a field of candidates dominated by ultra-conservatives.