Bombings hit two markets in Baghdad province on Thursday, killing at least 20 people, while gunmen shot dead five members of one family south of the capital, officials said.
Iraq is experiencing its worst violence since 2008, when it was emerging from a brutal sectarian conflict, and more than 250 people have been killed in just seven days.
Four bombs in a market north of the capital killed at least 13 people, while another hit a market in a predominantly Sunni neighbourhood in south Baghdad, killing seven.
The attacks also wounded more than 50 people, the officials said.
Militants in Iraq often bomb areas where crowds of people gather, and have struck markets, football pitches, cafes, mosques, weddings and funerals.
Also on Thursday, gunmen shot dead a man said to have been a former Sahwa anti-Al-Qaeda fighter, his three sons and one of their cousins south of Baghdad.
The Sahwa, who helped US forces from late 2006 to bring about a sharp reduction in violence, are frequently targeted by Sunni militants, who consider them traitors.
A magnetic "sticky bomb" on a car also killed a policeman and wounded two civilians in the northern city of Mosul.
A similar device killed an employee of a local television station and wounded a second in Baquba, also north of Baghdad.
And in the northern city of Kirkuk, a bomb killed a man and wounded his brother, while two alleged Al-Qaeda militants were shot dead by gunmen west of the city.
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The identity of the shooters was not immediately clear, but militants affiliated with Al-Qaeda and those from rival group Ansar al-Sunna have traded attacks in recent weeks.
Thursday's violence came a day after attacks in northern Iraq, including assaults by militants on local government and police buildings, killed 33 people.
There are persistent fears of a return to the all-out Sunni-Shiite sectarian violence that peaked in 2006-2007 and killed tens of thousands of people.
The UN Refugee Agency said this week it was "increasingly concerned about the situation in Iraq, where recent waves of sectarian violence threaten to spark new internal displacement of Iraqis fleeing bombings and other attacks."
Some 5,000 Iraqis have been displaced this year, joining more than 1.13 million who had previously fled or been forced from their homes, it said.
The latest violence takes the death toll to more than 700 people this month and more than 4,500 this year, according to AFP figures based on security and medical sources.
Diplomats and analysts say the Shiite-led government's failure to address the grievances of the Sunni Arab minority, who complain of political exclusion and abuses by security forces, has driven the spike in violence.
The government has made some concessions aimed at placating anti-government protesters and Sunnis in general, such as freeing prisoners and raising the salaries of Sunni anti-Al-Qaeda fighters, but underlying issues have yet to be addressed.
The civil war in neighbouring Syria has also fuelled sectarian tensions in Iraq.
In addition to major security problems, the government has also failed to provide adequate basic services such as electricity and clean water, and corruption is widespread.
Political squabbling has paralysed the government, and parliament has passed almost no major legislation in years.