The United Nations says Iraq accepts an international treaty banning chemical weapons.
The 1997 Chemical Weapons Convention bans the development, production, stockpiling and use of poison gas in warfare.
It will come into force for Iraq in 30 days.
The use of poison gas first came to prominence in World War I. The most widely used chemical weapons over the past century have been mustard gas, chlorine and nerve gas.
In 1988, former Iraqi leader Saddam Hussein used chemical weapons against Kurds suspected of siding with Iran. Iraq and Iran were at war at the time.
Thousands of Krds were killed in the ensuing Anfal campaign, including an estimated 5,000 people in the town of Halabja.
UN Secretary-General Ban Ki-moon congratulated Iraq on its decision to accede to the treaty, making it the 186th nation to do so.