- Jan 7 Impeachment trial of President Bill Clinton begins in the US Senate.
- Feb 12 US President Bill Clinton acquitted by the Senate in his impeachment trial
- Mar 29 The Dow Jones Industrial Average closes at 10006.78 - above the 10,000 mark for the first time ever
- Apr 7 The World Trade Organisation rules in favor of the United States in its long-running trade dispute with the European Union over bananas
- Apr 20 Columbine High School massacre: Eric Harris and Dylan Klebold kill 13 people and injure 24 others before committing suicide at Columbine High School, Colorado
- May 27 The International Criminal Tribunal for the former Yugoslavia indicts Slobodan Milošević and four others for war crimes and crimes against humanity committed in Kosovo
- Oct 12 The Day of Six Billion: the proclaimed 6 billionth living human in the world is born
Kosovo War: NATO commences air bombardment against Yugoslavia, marking the first time NATO has attacked a sovereign country.
On March 24, 1999
- Mar 13 Wiktoria Gąsiewska, Polish actress, born in Warsaw, Poland
- Mar 19 Tatum McCann, American actress
- Mar 23 Prince Beltran of Bulgaria
- Apr 3 Sam Kiszka, American bass player (Greta Van Fleet), born in Frankenmuth, Michigan
- May 23 James Charles [Dickinson], American internet personality and model (Cover Girl), born in Bethlehem, New York
NASA loses radio contact with the Mars Polar Lander moments before the spacecraft enters the Martian atmosphere
On December 3, 1999