The landmine exploded near a group of US soldiers in western Afghanistan, killing one and injuring four more, an American military statement aid on Wednesday.
The explosion occurred on Tuesday near a US military base in Shindand, close to the Iranian border, where the soldiers served in a military police unit, it said.
One of the wounded suffered a severe back injury, another was in stable condition, and two were treated and returned to duty, it added.
None of the soldiers were identified in the statement, which gave no further details.
As Taliban-led fighters continue to mount regular attacks on US and Afghan forces in the country, mainly in the south and east - although American commanders say that the former ruling militia is a fading force - the US is considering a long-term presence in the country.
On Wednesday, General Richard Myers, chairman of the Joint Chiefs of Staff, said during a visit to Afghanistan that he had yet to advise US President George Bush on whether to seek permanent American bases on Afghan soil.
"But clearly we've developed good relationships and good partnerships in this part of the world, not only in Afghanistan," Myers said at a news conference, also mentioning possible US bases in Uzbekistan and Kyrgyzstan.
"That'll all be considered as we go forward with the whole global basing construct," Myers said.
The Afghan government has said it is seeking a "strategic partnership" with the US as well as hi-tech weaponry and specialist training for its new US-trained national army.
The last American combat fatality occurred on 3 January, when fighters detonated two bombs and opened fire on American troops in eastern Kunar province, killing one soldier.
The day before that, one US soldier was killed in a gunfight when American troops tried to search a suspect's home near Shindand.