Nearly a million people take their own lives every year, more than those murdered or killed in war.
World Health Organisation figures show a suicide takes place somewhere in the world every 40 seconds.
The numbers are highest in Europe's Baltic states, where around 40 people per 100,000 commit suicide each year.
With World Suicide Prevention Day approaching on Friday, the WHO says the toll could be reduced with greater public awareness and political will.
"Suicide is a major public health problem and accounts for 1.5% of the total cost of disease to world society," said Jose Bertolote, mental health specialist at the WHO.
While men make up most suicides, more women actually attempt to take their own lives.
There are an estimated 10-to-20 million attempted suicides each year.
"Men usually resort to more definitive measures than women," says Lars Mehlum, president of the International Association for Suicide Prevention (IASP).
The elderly are statistically the most likely to kill themselves, though men aged between 15 and 29 are doing so more and more.
The IASP says this is largely because of the
availability of guns.
"Guns are the most lethal instrument of suicide. Few people
survive attempts to shoot themselves," Mr Mehlum said.
Some countries, like the United States, were resisting attempts to reduce the number in circulation, he said.
China, where 195,000 people committed suicide in the last year for which figures were available, is unusual in that female suicides outnumber male ones.
Mr Mehlum said the high rate among women in the Chinese countryside was down to their drinking highly toxic pesticides, which are often banned elsewhere.
He said tighter restrictions would cut the death rate.
Although the most recent figures from some countries are more than 20 years old, while others did not report at all, the WHO said a picture of world suicide rates could be assembled.
The biggest problem appears to be in the Baltic and former Soviet or communist states.
In 2000, in Lithuania, an estimated 42 people in
every 100,000 committed suicide. In Estonia the figure was 40 and in Russia 38.
The IASP suggested high alcoholism rates might explain the number of deaths in Eastern Europe.
In Lithuania the rate among men was more than 80 per 100,000.
The region with the lowest rate is Latin America.
There were few reliable figures for Africa.