A person is 10 times more likely to be shot dead in the US than in 22 other high-income countries, a study has found.
Gun homicide rates were 25 times higher in the US, the research showed.
While overall suicide rates were similar throughout the developed world, Americans were eight times more likely to use a gun to kill themselves.
The evidence, published in The American Journal of Medicine, is based on data gathered by the World Health Organisation in 2010.
Investigators found that the US had similar levels of non-lethal crime, but experienced far more fatal violence than other high-income countries, mostly due to guns.
Compared with the rest of the developed world, people in the US were seven times more likely to be violently killed, 25 times more likely to be a victim of gun homicide, eight times more likely to commit suicide with a gun, and 10 times more likely to suffer a firearm-related death overall.
Homicide - murder or manslaughter - was the second leading cause of death for young Americans aged 15 to 24, and the third leading cause of death among 25 to 34-year-olds.
US citizens in the younger age bracket were 49 times more likely to die from a homicidal act involving a gun than their counterparts in other high-income countries.
Professor David Hemenway, director of the Harvard Injury Control Research Centre and one of the research authors, said: "Differences in overall suicide rates across cities, states, and regions in the United States are best explained not by differences in mental health, suicide ideation, or even suicide attempts, but by availability of firearms.
"Many suicides are impulsive, and the urge to die fades away. Firearms are a swift and lethal method of suicide with a high case-fatality rate."
The investigators found that despite having only half the population of the other 22 high-income nations combined, the US accounted for 82% of total firearm deaths.
"Overall, our results show that the US, which has the most firearms per capita in the world, suffers disproportionately from firearms compared with other high-income countries," said co-author Dr Erin Grinshteyn, from the University of Nevada-Reno.
"These results are consistent with the hypothesis that our firearms are killing us rather than protecting us."