At least 65 people were killed in a triple bombing that targeted a tent filled with mourners in Baghdad's Shia Muslim stronghold of Sadr City.
A car bomb went off near the tent where a funeral was being held.
A suicide bomber driving a car then blew himself up, and a third explosion followed as police, ambulances, and firefighters were gathering at the scene.
No group immediately claimed responsibility for the attack, in which at least 120 others were wounded.
Delicate sectarian balance under growing strain
In a separate incident, at least eight people were killed when a car bomb exploded in a busy street in the predominantly Shia Ur district of northern Baghdad.
Iraq's delicate sectarian balance has come under growing strain from the civil war in neighbouring Syria, where mainly Sunni Muslim rebels are fighting to overthrow a leader backed by Shia Iran.
Both Sunnis and Shia have crossed into Syria from Iraq to fight on opposite sides of the conflict.
Al-Qaeda's Iraqi and Syrian branches merged earlier this year to form the Islamic State of Iraq and the Levant, which has claimed responsibility for attacks on both sides of the border.
Around 800 Iraqis were killed in acts of violence in August, according to the United Nations.
Earlier today, four attackers killed six officers in an assault on a police station in Baiji, about 160km north of Baghdad.
No group immediately claimed responsibility for the attack, in which at least 100 others were wounded medics said.