The deadliest of the attacks was in the city of Hillah, where back-to-back explosions in a busy commercial area killed at least 27 people and wounded up to 90, a police officer said. Insurgents first detonated a roadside bomb that was followed by a car bomb explosion when rescuers rushed to the scene, he added.
Among the victims in Hillah, 95 kilometers (60 miles) south of Baghdad, were Shiite mourners who were commemorating the 17th century martyrdom of the Prophet Muhammad's grandson, Imam Hussein, he added.
Twisted and charred remains of vehicles were seen outside damaged shops as shop owners collected their strewn merchandise from the bloodstained pavement, littered with debris.
Just hours earlier, a parked car bomb went off at one of its gates of the city of Karbala in the nearby province by the same name, killing six people and wounding 20, another police officer said. The explosion took place less than one kilometer (half mile) away from the shrine of Imam Hussein.
Shiite religious ceremonies have often been targeted by Sunni militants who view the Shiites as heretics. Iraq has seen repeated deadly attacks against Shiites commemorating the anniversary of Imam Hussein's death, but Thursday's attacks were the deadliest since ceremonies started last Sunday.
Karbala, 90 kilometers (55 miles) south of Baghdad, is one of the holiest cities in Shiite Islam and the place where Imam Hussein and his brother, Imam Abbas, are buried. Hundreds of thousands of Shiites flock to their golden-domed shrines every year.
Also Thursday, a suicide bomber drove his explosives-laden car into a police checkpoint in the city of Fallujah, 65 kilometers (40 miles) to the west of the capital, killing three policemen and wounding 11 others, another police official said.
And in the northern city of Mosul, a parked car bomb went off next to a passing police patrol, killing two people and wounded two, police said. Another police patrol was hit by a roadside bomb in the in the town of Balad Ruz, 70 kilometers (45 miles) northeast of Baghdad, killing one policeman and wounding six others.
Three health officials confirmed the causality figures. All officials spoke on condition of anonymity because they were not authorized to talk to the media.
Although violence has ebbed since the peak of insurgency several years ago, attacks are still frequent against security forces, government officials and civilians. No one claimed responsibility for Thursday's bombings, but car bombs, shootings and roadside devices are the hallmark of al-Qaida in Iraq.