January 12 – Valencia becomes a component city in the province of Bukidnon through ratification of Republic Act 8985.[1]
January 16 – After 11 senators voted not to open an envelope containing potentially incriminating documents against President Estrada, the prosecutors walk out.
Cauayan becomes a component city in the province of Isabela through ratification of Republic Act 9017.[7]
Voters of the municipality of Meycauayan in the province of Bulacan reject the cityhood law under the Republic Act 9021 which sought to convert the town into a component city.
May 27 – Twenty individuals, among them 13 tourists and 3 staff members, are seized by the Abu Sayyaf Group (ASG) guerrillas from an island resort in Palawan, and are taken to Basilan; some of them are killed; crisis lasts about 12 months. The captives include Americans Guellermo Sobero, who would be found dead in October, and the Burnhams, missionaries who would remain in captivity until a rescue attempt in June 2002.[10][11]
June 1–3 – Series of battles in Basilan between the military and the Abu Sayyaf leave two deaths, while nine of the hostages from Palawan escape. The guerrillas seize the hospital in Lamitan, wherein they took additional hostages.[11]
November 19–29 – Another group of Misuari partisans under his nephew Julhambri begin to occupy the Cabatangan complex, the ARMM satellite office in Zamboanga City.[19][20] On November 27, a massive military assault forces the rebels to leave the facility[20][21] as they capture up to at least 118 hostages,[22] and meet up with other Misuari followers in another barangay;[20] thirty rebels, a soldier and a civilian are killed in a standoff.[20] The rebels release the hostages until November 28[22][23] through their agreement with the government, in exchange for their safe evacuation[22] to a MNLF camp in the outskirts of the city; ending a hostage crisis.[23] On November 29, a number of MNLF holdouts attacked troops at the said complex;[23] six of them are captured.[22][a]
As per Executive Order No. 292, chapter 7 section 26, the following are regular holidays and special days, approved on July 25, 1987.[24] Note that in the list, holidays in bold are "regular holidays" and those in italics are "nationwide special days".
^According to a news report by The Philippine Star, the number of MNLF rebels involved in the Zamboanga City siege, originally at some 60, later increases to 200 prior to the November 27 military attack;[20] another report later states more than 300.[23] Meanwhile, that of holdouts involved in another fighting ranges from 30[23] to 40.[22]