About a quarter of the deaths occurred in Iraq
The US army has said the number of suicides in the military last year was the highest since records began, with 115 recorded.
The year saw increased violence in Iraq and Afghanistan, and about a quarter of the suicides happened in Iraq.
The extension of deployments from 12 to 15 months added to the strain on soldiers serving abroad.
Democratic presidential hopeful Barack Obama called the figures a tragic reminder of the costs of the Iraq war.
The figure of 115 deaths in 2007 represents an increase of almost 13% over the number for 2006, an army source told the Associated Press.
A military official acknowledged that the wars were having an effect.
"Mainly it is the long time and multiple deployments away from home, the exposure to really terrifying and horrifying things, the easy availability of loaded weapons, and, of course, it's very, very busy right now," said Col Elspeth Ritchie.