The military said the helicopter was conducting a combat air patrol when it went down in an area "known for terrorist activity." Officials said it was too early to determine the cause of the crash, and the names of the two dead soldiers were not released.
Video footage shot by AP Television News in Mishahda, north of Baghdad, showed smoke billowing from what was reported to be the crash site. Other helicopters could be seen circling nearby.
In a video posted on an Internet site known for its militant content, a group calling itself the Mujahedeen Army claimed responsibility for shooting down the helicopter.
The wobbly video showed what appeared to be a helicopter flying in the distance. A militant is seen firing a shoulder-launched missile that heads for the helicopter, which is apparently hit and catches fire before crashing. Men are heard shouting in celebration over the apparent downing.
The authenticity of the video couldn't be verified.
Another group, the Salahudin al-Ayoubi Brigade, also claimed to have shot down the helicopter in an Internet posting. That claim also could not be verified.
In other developments:
Rashid Khalifa, 27, who has a food and drink stand in the area, said he witnessed the attack.
"I saw the smoke trail left by the missile," he said. "I heard a hissing sound looked around and saw the helicopter losing control before crashing down."
Among the helicopters used by the Army that have a two-person crew are the AH-64 Apache and the OH-58 Kiowa reconnaissance.
The number of fatal U.S. military helicopter crashes in Iraq has spiked in recent weeks, fitting a wartime pattern of more frequent accidental and combat crashes during winter months.
An OH-58 Kiowa Warrior reconnaissance helicopter crashed near Mosul on Friday, killing two pilots. On Jan. 7, a Black Hawk with 12 aboard crashed in bad weather near the northern city of Tal Afar. All eight soldiers and four civilians aboard were killed.
The causes of those crashes haven't yet been announced.
The overall safety record of Army and Marine Corps helicopters has been good, military officials and private analysts say, given the enormous amount of flying in often-harsh conditions.
Army helicopters alone have logged nearly 1 million flight hours since the war began, with the UH-60 Black Hawk accounting for nearly one-third of the total, according to Army Aviation Warfighting Center records.
A total of seven Black Hawks have crashed during the war. The second-most heavily used Army helicopter, the AH-64 Apache, has crashed four times and the No. 3 helicopter, the Kiowa Warrior, has gone down seven times. Some were accidents, others were caused by hostile fire and some are still under investigation.