Flags out for the national "Victory Day"
A gun salute marked the beginning of the "Victory Day" at a war memorial near Dhaka.
President Badruddoza Chowdhury and Prime Minister Khaleda Zia led the country in paying tributes to its war dead.
Politicians of the main opposition Awami League also placed wreaths, although leader Sheikh Hasina Wajed, the daughter of Sheikh Mujibur Rahman, who led the war against Pakistan, was not present.
She is reported to be on a private visit to the United States.
Crowds of people, many carrying flowers, gathered at the memorial.
Formerly East Pakistan, Bangladesh came into being in 1971 when the two parts of Pakistan split after a bitter civil war which drew in neighbour India.
Bangladesh spent 15 years under military rule and although democracy was restored in 1990, the political scene remains volatile.
Bitter feud
Much of the country's politics revolves around a vitriolic personal feud between two women - the Prime Minister, Khaleda Zia and her rival, Sheikh Hasina.
Analysts say the antagonism between the governing Bangladesh Nationalist Party and the Awami League, which governed until July 2001, reflects personal animosity between their leaders rather than substantial ideological differences.
The Awami League is seen as more pro-Indian and left-leaning, while the BNP is viewed as more pro-Pakistani.
Tension between the two parties was heightened before the general elections in October.
There were frequent clashes between supporters of the two parties and the campaign, which killed more than a hundred people, was described as one of the most violent.
Awami League lost the elections, termed the vote as rigged and announced a boycott of the new parliament.
Some analysts say boycott of the house had been used as a political tool by both the main parties.