Thirty-five US soldiers were wounded in a fierce mortar attack late Wednesday, the US military said in a statement.
Insurgents fired six mortar rounds that rocked a US logistical base west of Baghdad after sundown, said the statement.
Thirty-five soldiers from the 3rd Corps Support Command have been wounded and received emergency treatment at medical facilities, added the statement.
It was not clear about the types of the injuries or the condition of the soldiers, and a CNN reporter said the details could be available before daybreak.
Mortars were frequently used by resistance fighters in Iraq, especially in the so-called Sunni Triangle north and west of Baghdad.
Though no death toll was announced, Wednesday night's assault appeared to be one of the most deadly in a series of unabated anti-US attacks following the capture of Saddam Hussein on Dec. 13.
A total of 331 US soldiers have been killed by hostile fire in Iraq since the US-led coalition forces launched the war on Iraq last March.