At least 90 people were wounded in the wave of attacks that stretched from the oil-rich city of Kirkuk
people and wounded 90, officials said, in the latest instance of what appeared to be co-ordinated violence.
The deadliest attack came in the town of Taji, a former al-Qaeda stronghold just north of Baghdad, where three explosive-rigged cars went off within minutes of each other on Sunday morning.
Police said eight people died and 28 were injured in the back-to-back blasts that began around 7:15am local time.
In all, at least 90 people were wounded in the wave of attacks that stretched from the oil-rich city of Kirkuk in Iraq's north to the southern Shia town of Kut.
Spokesmen for the government and Baghdad's military command could not immediately be reached for comment, and no one claimed responsibility for the violence immediately.
Hakim al-Zamili, a member of parliament's security and defence committee, said the attacks were a sign al-Qaeda "is still in business".
He said a deadly weekend prison break in Tikrit in which many al-Qaeda-linked convicts escaped, likely boosted the network's morale and spurred Sunday's assault.
"Al-Qaeda leaders have no intention of leaving this country or letting Iraqis live in peace," al-Zamili said.
"Thus, we should expect more attacks in the near future. The situation in Iraq is still unstable ... and repetition of such attacks shows that our security forces are still unqualified to deal with the terrorists," he added.
Al Jazeera's Jane Arraf, reporting from neighbouring Jordan, said al-Qaeda has been indisputably weakened over the last years.
"Since the group rose to prominence in the wake of the US invasion, al-Qaeda has made a series of blunders, if you will, that meant that there was far less support for them, even among the communities where you'd expect there to be support," our correspondent said.
"The tribes turned against them, they were severely weakened. So it is not the al-Qaeda that we knew, but it is amazingly resilient and it is clearly still there."
Shortly after the Taji attacks, police said a suicide bomber set off his explosives-packed car in the Shia neighborhood of Shula in northwest Baghdad.
One person was killed and seven wounded. Police could not immediately identify the target.
"So many people were hurt. A leg of a person was amputated," lamented Shula resident Naeem Frieh. "What have those innocent people done to deserve this?"
And in Baghdad's bustling Karradah neighbourhood, a parked car laden with explosives went off next to a police patrol, killing a police officer and a civilian, other officials said.
Eight other people were injured. The blast was followed minutes later by another parked car bomb as people gathered, killing three civilians and injuring 12 others, they added.
Secondary bomb blasts targeting those coming to help the wounded are a common insurgent tactic.
An Associated Press cameraman was knocked to the ground in the second explosion and an AP photographer was slightly injured.
Police officers targeted
Elsewhere in the country, another suicide bomber drove a minibus into a security checkpoint in Kut, located 160 kilometres southeast of Baghdad.
Three police officers were killed and five wounded, general Hussein Abdul-Hadi Mahbob said.
And in Iraq's north, another policeman was killed when security forces were trying to defuse a car bomb parked on the main highway between the cities of Kirkuk and Tuz Khormato, said Kirkuk police chief general Sarhad Qadir.
A second policeman was wounded in the blast, Qadir said.
In mid-morning, another parked car bomb went off next to a bus carrying Iranian pilgrims in the town of Madain, killing three Iraqis and injuring 11 others including seven Iranians, another police officer and health official said.
In the town of Balad Ruz, 75 kilometres northeast of Baghdad, a parked car bomb targeted a passing police patrol, killing two policemen and injuring seven others, a police officer and health official said.
And in the nearby town of Khan Bani Saad, yet another parked car bomb exploded near a market and killed one civilian and injured nine others, they added.
Two Iraqi soldiers were killed in the town of Tarmiyah, 50 kilometres north of Baghdad, when their patrol hit a roadside bomb, another police officer and health official said. Six other people, including four civilians were wounded.
Earlier this summer, the Iraqi wing of al-Qaeda, also called the Islamic State of Iraq, launched a campaign dubbed "Breaking the Walls," which aimed at retaking strongholds from which it was driven by the American military.
Violence has dropped since the height of Iraq's bloodshed a few years ago, but Iraqi forces have failed to stop the attacks that continue to claim lives almost daily