One in 10 people says they or a member of their household has paid a bribe in the past year, according to a global opinion survey published on Thursday.
The World Bank estimates that more than $1,000bn is paid out in bribes every year
It suggests that Cameroon is the most corrupt country, as a majority of those surveyed there admitted paying bribes.
It was followed by Nigeria, Kenya, Lithuania and Moldova - all countries where at least one in three people admitted paying bribes.
Transparency International released its poll to mark UN Anti-Corruption Day.
It was based on the responses of more than 50,000 people in 64 countries
While most countries where a high level of bribery was reported were relatively poor, there were exceptions to this rule.
Some 11% of Greeks reported that they or a member of their household had paid a bribe in the past year.
South Africans, by contrast, admitted paying bribes at similarly low levels to most developed countries.
Parties 'most corrupt'
People across the world perceive political parties as the institutions most affected by corruption, the survey suggests.
They are followed by parliaments, police and the judiciary in being seen as corrupt.
Akere Muna, a Transparency International board member and president of the anti-corruption body's Cameroon branch, said: "It is time to use international co-operation to enforce a policy of zero tolerance of political corruption, and to put an end to practices whereby politicians put themselves above the law - stealing from ordinary citizens and hiding behind parliamentary immunity.
"Political parties and the politicians they nominate for election are entrusted with great power and great hopes by the people who vote for them. Political leaders must not abuse that trust by serving corrupt or selfish interests once they are in power."
The survey was conducted for Transparency International by Gallup International as part of its Voice of the People Survey between June and September 2004.
The Berlin-based pressure group, founded by a former World Bank official after he encountered corruption in Africa, has been a prime mover behind the idea of the UN World Anti-Corruption Day
Events are being held in several countries on Thursday to mark the first such day. It aims to highlight the scale of the problem and efforts to fight it.
Nations including Bangladesh, Germany, Colombia and Morocco are marking the occasion with workshops, rallies, and the release of research.
The World Bank estimates that more than $1 trillion is paid out in bribes every year around the globe.
This particular date, 9 December, was picked as it marks the first anniversary of the launch of the UN convention against corruption at a conference in Mexico.
The anti-bribery rules set out in the convention will come into force when 30 countries have signed up to it - so far 12 have, according to Transparency International.