Smoking killed almost five million people around the world in 2000, researchers have calculated.
Harvard University and the University of Queensland say over half the deaths were in smokers aged 30 to 69.
The research, in the journal Tobacco Control, found premature death rates were evenly split between the developed and developing world.
But men were over three times as likely as women to die an early death as a direct result of smoking.
The researchers used detailed statistical analyses as well as population and mortality data to arrive at their figures.
Three out of four smoking deaths in developed countries and more than eight out of 10 in developing countries were in men.
The leading cause of smoking related death was cardiovascular disease, which killed over 1 million people in the developed world and 670,000 in the developing one.
Lung cancer, the next biggest smoking killer in the developed world, sent over 500,000 people to an early grave.
Chronic obstructive airways disease (COPD), a collective term for inflammatory lung disease, such as bronchitis, killed more people in the developing world, accounting for 650,000 deaths.
In Eastern Europe and North America, smoking caused almost one in four deaths among people aged between 30 and 69.
And in developing countries overall, 62% of deaths directly attributable to smoking were in people aged between 30 and 69, compared with around half in industrialised countries.
The overall increase in smoking around the world in the last quarter of the 20th century accounts for one in 10 of all deaths among adults and almost one in five of those among men.
Future looks bad
Writing in the journal, the researchers warn that the death toll from smoking is likely to continue to rise.
“The health consequences of smoking will continue to grow unless effective interventions and policies that curb and reduce smoking among [men] and prevent increases among [women] in these countries are implemented.”
Amanda Sandford, of the anti-smoking charity Ash, said the research graphically illustrated the “devastating impact” of smoking on communities around the globe.
She said: “The extent of lung cancer, heart disease and chronic respiratory disease in millions of people is a direct consequence of the ruthless marketing of a deadly drug by the multi-national tobacco companies.
“We must not forget that behind these bald statistics are real people: mothers, fathers, friends and other loved-ones who have suffered needlessly and who may have lost up to 30 years of life because of their addiction.
“If we are to stem this dreadful tide of mortality in the future, governments must implement the global tobacco control treaty without delay.”
The tobacco control treaty was negotiated last year by the World Health Assembly.
It requires countries to ban or impose tough restrictions on tobacco advertising, sponsorship and promotion within five years.
It also lays down guidelines on health warnings to be carried on cigarette packets, recommends tax increases on tobacco products and calls for a crackdown on cigarette smuggling, amongst other measures.
Simon Clark, of the smokers’ rights group Forest, said: “No-one disputes the health risks of long-term heavy smoking but before politicians and researchers use these figures to demonise all smokers, it is important to consider other factors such as the effect of diet, including malnutrition, and lack of proper exercise.
“In Britain smoking rates have dropped from 45% in 1974 to 26% today.
“The estimated number of smoking-related deaths is falling and smoking is already banned in many public places, with more restrictions on the way.
“If we believe that adults should accept a large degree of responsibility for their own health, further government intervention to curb and reduce smoking would be wholly inappropriate.”