2003 (MMIII, in Roman numerals) was a common year of the 21st century that began on a Wednesday, according to the Gregorian calendar. Its Sunday letter was E. Shrove Tuesday took place on March 4th and Easter Sunday on April 20th. According to the Chinese horoscope, it was the year of the Goat, starting on February 1st.
It was designated as the International Year of Drinking Water by the UN.
Foundation of the Social and Parish Center of the Cathedral of Angra do Heroísmo.
Restoration and expansion of the pipe organ of the Cathedral of Angra do Heroísmo.
January 1 - Luiz Inácio Lula da Silva assumes the presidency of the Federative Republic of Brazil.
January 2 - Chavez visits Lula in Brasília and proposes energy integration between Latin American countries
January 11 - The new Brazilian Civil Code, approved by Congress in September 2001, enters into force.
January 24 - Rapper "Sabotage" is murdered.
January 30 - France seizes Varig's Boeing for non-payment of the leasing contract by Varig.
February 1 – Space shuttle Columbia disintegrates during mission STS-107's re-entry into Earth's atmosphere, killing all seven astronauts on board.
February 17 - Premieres Mulheres Apaixonadas, a soap opera written by Manoel Carlos and shown by Rede Globo, which breaks audience records on Brazilian TV.
25 February - The European Union reaches an agreement on "the first legal immigration instrument", a draft EU directive on the right to family reunification of immigrants.
Roh Moo-hyun assumes the presidency of South Korea.
February 28 - The COMPOMUS (Musical Composition Laboratory) of the Federal University of Paraíba (UFPB) is inaugurated.
March 3 - Foundation of Associação Atlética Coruripe, football club in Alagoas.
March 4 - Carnival - Gaviões da Fiel wins the São Paulo carnival and wins its 4th title in the school's history, with a plot that spoke about the five Brazilian regions.
March 5th - Carnival - Beija-Flor from Nilópolis wins the carioca carnival; is the seventh title of the school
March 6 - Cuba's National Assembly re-elects leader Fidel Castro for another five-year term as president.
16 March - José Durão Barroso, 1st Minister of Portugal, hosts the Summit of Lajes, Azores, where he receives Tony Blair, George W. Bush and José Maria Aznar to arrange the invasion of Iraq, despite several anti-war demonstrations taking place in European cities, including Lisbon, Madrid and London.
March 19 - US-led coalition launches war in Iraq against Saddam Hussein.
March 24 - 400th anniversary of the death of Queen Elizabeth I of England.
March 31 - The President of the Republic, Luiz Inácio Lula da Silva, announced an increase in the minimum wage from 200 to 240 reais.
April 14 – The Human Genome Project is finalized, with 99% of the DNA sequenced to an accuracy of 99.99%.
April 21 - Death of singer Nina Simone
April 27 - Beatification of Tiago Alberione by Pope John Paul II.
May 1 – US President George W. Bush, in a speech, announces the end of the biggest military operation of 2003: the Invasion of Iraq.
2 May – The Portuguese Navy lowered the Portuguese flag for the last time at the São Sebastião Fort, Angra do Heroísmo, giving rise to a maintenance and recovery intervention. The property was thus reclassified as one of the Pousadas de Portugal, inaugurated in 2006, with the status and classification of "Historic Design Inn", putting an end to 469 years of its presence on the site.
May 16 - Total lunar eclipse seen mostly in the Americas.
May 21 - An earthquake hits the northern region of Algeria and leaves 2,200 people dead.
May 25 - Néstor Kirchner assumes the Presidency