October 1999 : January - February - March - April - May - June - July - August - September - October - November - December

• October - NASA loses one of its probes, the Mars Climate Orbiter
• October 5 - Thirty-one people die in the Ladbroke Grove rail crash, west of London, England.
• October 12 - Pakistani Prime Minister Nawaz Sharif attempts to dismiss Army Chief General Pervez Musharraf and install ISI director Khwaja Ziauddin in his place. Senior Army generals refuse to accept the dismissal. Musharraf, who was out of the country, attempts to return in a commercial airliner. Sharif orders the Karachi airport to not allow the plane to land. The generals lead a coup, ousting Sharif's administration and taking over the airport. The plane lands with only a few minutes of fuel to spare, and Musharraf takes control of the government.
• October 12 - The 6 billionth person in the world, according to the UN is born in Sarajevo, Bosnia and Herzegovina.
• October 13 - The United States Senate rejects ratification of the Comprehensive Test Ban Treaty (CTBT)
• October 15 - National Geographic Society reveals the fossil of Archaeoraptor in a press conference (the fossil is later found to be a forgery)
• October 18 ? Michael Pawluk Michigan attorney sails solo-single-handed over 2,500 nautical miles (4600 km) on a 30 foot (10 m) boat when his wife demands "some space".
• October 25 - Golfer Payne Stewart, 42, dies in an aircraft accident.
• October 27 - Gunmen open fire in the Armenian parliament killing Prime Minister Vazgan Sarkisian, Parliament Chairman Karen Demirchian and 6 other members.
• October 27 - The New York Yankees complete a 4 game sweep of the Atlanta Braves to win their second consecutive World Series.
• October 31 - EgyptAir Flight 990 traveling from New York City to Cairo crashes off the coast of Nantucket, Massachusetts, killing all 217 on-board
• October 31 - Roman Catholic Church and Lutheran Church leaders sign the Joint Declaration on the Doctrine of Justification, ending a centuries-old doctrinal dispute over the nature of faith and salvation.
• October 31 - Nerf Arena Blast is released by Atari, Inc. and Visionary Media, Inc.

1999