It is typically one of the most festive dates on the Muslim calendar. Eid al-Fitr marks the end of Ramadan and the beginning of three days of celebrations.
Sunni Muslims in Iraq observed the start of Eid on Monday, Shi'ites will follow a day or two later. But throughout Iraq, the festival has already been marred by reports of more sectarian violence.
In Baghdad, a series of market bombings killed at least nine people on Sunday.
Baghdad resident Hassan Karim says everyone there hopes Eid will help ease tensions in the divided city.
He says Ramadan has been especially hard on Iraq, and, God willing, the Eid will bring some relief from the bombings, sadness and fear.
Baghdad's six-million residents are roughly divided between Sunni and Shi'ite Muslim communities.
And, despite stepped up security in recent weeks, the city remains the flashpoint in the country's sectarian conflict.
On Monday, normally crowded Sunni mosques reported a major decline in worshippers. The city's predominantly Sunni neighborhoods were also uncharacteristically quiet, as frightened residents celebrated the holiday indoors.
October has also been particularly hard on U.S. forces in Iraq. Another five American troops were reported killed Sunday.
The total U.S. casualty count this month is at 85, the highest monthly death toll since 2004.