In the deadliest attack, at least 16 people died after a car packed with explosives blew up at a procession of pilgrims in the Al-Nil area, near the city of Hillah.
Pilgrims were also targeted in the center of Hilla, in the towns of Latifiya and Mahawil, and in the capital, Baghdad.
The attacks in central Iraq came a day before the peak of the Shi'ite Ashura religious commemorations marking the death of the Prophet Muhammad's grandson, Imam Hussein.
Ashura has witnessed serious sectarian violence since the U.S.-led invasion of Iraq in 2003, with pilgrims often targeted by Sunni extremists.
The attacks underscored Iraq's fragile security as U.S. troops prepare to withdraw by the end of 2011.
compiled from agency reports