Car bombs have hit several mostly Shia neighbourhoods of the Iraqi capital and other areas across the country, killing at least 18 people and wounding dozens, officials said.
Wednesday's attacks are the latest bout of violence ahead of the country's first parliament elections since the 2011 US troop withdrawal.
The explosions also coincided with the anniversary of the 2003 fall of Baghdad in the hands of US troops.
Earlier in the day, a car bomb in Baghdad's central Nidhal Street killed four people and wounded 11, while three people died and nine were wounded in a car bombing in the northern Kadhimiyah district, the AP news agency reported.
Car bombs also exploded in the areas of Shaab, Shammaiya, Karrada and Maamil, killing a total of seven people and wounding 30, police officials added.
Later on Wednesday, three more civilians died and eight were wounded when another car bomb struck Baghdad's central upscale commercial area of Jadiriyah.
In the Saba al-Bur area north of Baghdad, two mortar rounds killed at least one person and wounded at least five.
Medical officials confirmed the causality figures.
Violence has surged in Iraq since last year, with the country weathering its deadliest bout of violence since it pulled back from the brink of civil war in 2008.
UN figures showed that last year, Iraq saw the highest death toll in attacks, with 8,868 people killed.
Too dangerous to vote
Wednesday's attacks came as Iraq is heading towards a crucial election on April 30, its first vote since the 2011 US troop pullout.
More than 9,000 candidates will vie for 328 seats in parliament but there will be no balloting in parts of the western, Sunni-dominated Anbar province engulfed in clashes between security forces and al-Qaeda-inspired fighters.
On Tuesday, the country's Independent High Electoral Commission said those areas were too dangerous for the vote to take place.
Since late December, Anbar province has seen fierce fighting between government troops and allied tribal fighters on one side, and fighters from the Islamic State of Iraq and the Levant, an al-Qaeda spin-off group, on the other.