A bomb exploded in the Omar bin Abdulaziz Mosqe in the northern city of Kiruk, while another blast struck near Al-Salihin Mosque close by, killing a total of seven people and wounding 41.
And a car bomb exploded near Al-Imam Ali Mosque in Kut, southeast of Baghdad, killing two people and wounding nine.
Special extended evening prayers are held during the holy Muslim fasting month of Ramadan, which began two weeks ago.
Both Sunni and Shiite places of worship have been attacked in recent months, raising fears of a return to the all-out sectarian conflict that killed tens of thousands of people in past years.