Iraqi officials said at least 15 people were killed when a suicide bomber detonated explosives at a Shi'ite mosque in western Baghdad on October 19.
The blast in the Harthiya neighborhood also wounded nearly 30 people, security and medical officials said.
The attack was the latest in a surge of bombings that have hit Baghdad over the last month, most of them claimed by the Islamic State (IS) militants.
Elsewhere in Iraq, IS militants staged a suicide attack on Iraqi government forces on October 19 to halt their advance on Baiji, a key town in the country's north.
Baiji, which is adjacent to Iraq's largest oil refinery, is controlled by the militant group.
Iraqi forces launched an operation on October 18 to retake the town.
But the operation was snarled when an armored vehicle blew up near the security forces convoy south of Baiji, killing four soldiers and wounding seven.