The 1999 Armenian parliament shooting, commonly known in Armenia as October 27, was a terrorist  attack on the Armenian National Assembly in the capital of Yerevan on 27 October 1999 by a group of five armed men led by Nairi Hunanyan that, among others, killed the two de facto decision-makers in the country's political leadership—Prime Minister Vazgen Sargsyan and Parliament Speaker Karen Demirchyan. Their reform-minded coalition had won a majority in a parliamentary election held in May of that year and had practically sidelined President Robert Kocharyan from the political scene.

The shooting led to significant changes in the country's political landscape. It remains a subject of numerous conspiracy theories, mostly involving President Kocharyan, whose tenure thereafter was frequently criticized as authoritarian. Sargsyan and Demirchyan were posthumously honored with National Hero of Armenia titles.

On 27 October 1999, at around 5:15 p.m. five men led by journalist Nairi Hunanyan, armed with Kalashnikov AK-47 rifles hidden under long coats, broke into the National Assembly Building in Yerevan, while the government was holding a question-and-answer session. They shot dead eight people:

• Vazgen Sargsyan, Prime Minister
• Karen Demirchyan, National Assembly Speaker
• Yuri Bakhshyan, Deputy National Assembly Speaker
• Ruben Miroyan, Deputy National Assembly Speaker
• Leonard Petrosyan, Minister of Urgent Affairs
• Henrik Abrahamyan, Member of Parliament
• Armenak Armenakyan, Member of Parliament
• Mikayel Kotanyan, Member of Parliament

The gunmen injured at least 30 people in the parliament.

Hunanyan was accompanied by his brother Karen, uncle Vram, and two others. The group claimed they were carrying out a coup d'état, describing their act as "patriotic" and "needed for the nation to regain its senses."They said they wanted to "punish the authorities for what they do to the nation" and described the government as profiteers "drinking the blood of the people." They claimed Armenia was in a "catastrophic situation" and that "corrupt officials" were not doing anything to provide the way out.Vazgen Sargsyan was the main target of the group and the other deaths were said to be unintended. According to reporters who witnessed the shooting, the men went up to Sargsyan and said, "Enough of drinking our blood," to which Sargsyan calmly responded, "Everything is being done for you and the future of your children." Sargsyan was hit several times. Hunanyan claimed that the eight deaths and dozens of injuries in the attack were all "innocent victims" except for the case of Sargsyan, who he said had "failed the nation". Anna Israelyan, a journalist who witnessed the incident, stated that "the first shots were fired directly at Vazgen Sargsyan at a distance of one to two meters" and, in her words, "it was impossible that he would have survived." Gagik Saratikyan, a cameraman, was the first person from outside to be allowed to go into the building while the men were in control of it. Saratikyan recorded the dead bodies of Sargsyan and Demirchyan. Sargsyan's body was taken out of the parliament building on the evening of 27 October.

Soon after the attack, hundreds of policemen and military personnel and two armored personnel carriers were brought into Yerevan, positioned on Baghramyan Avenue surrounding the National Assembly building. Meanwhile, ambulances rushed to the site of the shooting. President Robert Kocharyan was directing the operation of the security forces around the parliament building. While holding around 50 hostages inside the building, the men demanded a helicopter and airtime on national television for a political statement.

President Kocharyan gave a speech on television announcing that the situation was under control. His spokesman was quick to characterize the men as "individual terrorists" and assured that "it's only the parliament building and a very small group."After overnight negotiations with President Kocharyan, the gunmen released the hostages and gave themselves up on the morning of 28 October after a standoff that lasted 17–18 hours. Kocharyan had guaranteed the personal security of the gunmen and the right to a free trial. In the meantime, the Armenian armed forces blocked the roads leading to Yerevan for security reasons.

On 28 October 1999, President Kocharyan declared a three-day mourning period. The state funeral ceremony for the victims of the parliament shooting took place from 30 October to 31 October 1999. The bodies of the victims, including Sargsyan, were placed inside the Yerevan Opera Theater. Karekin II, the Catholicos of All Armenians, and Aram I, the Catholicos of the Holy See of Cilicia, gave prayers.