Three car bombs and a suicide bomber have targeted food markets in towns north of Baghdad.
The most deadly of the attacks on June 10 was at a produce market outside the mainly Shi'ite city of Baquba.
Two car bombs exploded and a suicide bomber in another vehicle detonated his explosives in the town of Jadidat al-Shatt, about 40 kilometers from Baghdad, during the height of business hours, killing at least 13 people and wounding about 50 others.
Later, another car bomb exploded at a fish market in the town of Taji about 25 kilometers from Baghdad.
It killed at least seven people and wounded 16.
No one immediately claimed responsibility for the attacks, but suspicion has fallen on a group known as the Islamic State of Iraq, an organization linked to Al-Qaeda.
Baquba is one of the most dangerous places in Iraq.
More than 40 people were killed in the city last month when a bomber struck outside a mosque as people were leaving Friday Prayers.
May was the bloodiest month in Iraq since 2008, as sectarian violence flared between the country's Shi'ite majority and minority Sunnis.
Based on reporting by Reuters, AFP, and AP