A car bomb in a popular Baghdad market killed eight people and wounded 30, while another killed two people and wounded 15 in Taji, 25 kilometres (15 miles) north of the capital, the officials said.
Further north, in the city of Samarra, gunmen killed two anti-Qaeda militiamen and wounded two more at a roadblock, the officials added.
In the town of Baquba, northeast of Baghdad, two people were killed and four wounded in a bomb attack, police sources said, adding that three more people were wounded in a separate blast.
And five people were wounded in the former insurgent town of Ramadi west of Baghdad when a car bomb exploded in a city centre parking area belonging to a state-run immigration office, the sources added.
Thursday's deaths brought to more than 200 the number of people killed in Iraq since June 13 -- more than were killed in all of May.
Attacks on June 13, which killed 72 people across the country, were later claimed by Al-Qaeda's front group, the Islamic State of Iraq.
Two car bombs targeting Shiites commemorating the death of a revered imam killed 32 people in the capital on June 16.
Two days later, a suicide bomber killed 22 people in an attack on Shiite mourners in Baquba, north of Baghdad.
On Wednesday, three bombings killed 11 people, security and medical officials said.
Violence has declined significantly since its peak in 2006 and 2007, but attacks remain common, killing 132 people in May, government figures show.