The renewed violence came after the resignation of US Defense Secretary Donald Rumsfeld after mid-term elections.
At least 24 people were killed in Baghdad itself, with at least eight explosions in the capital.
The highest number of fatalities were caused by a suicide car bomb near the Mishin shopping center, in the southeast. It killed seven people and wounded 27.
Police said a mortar shell was fired at the site to lure people in before the car bomber detonated his vehicle, ensuring maximum casualties.
A bomb then exploded in the Suq Haraj market in the Bab al-Sharqi area, killing three and wounding 19, a medic at Al-Kindi hospital said.
Later, a suicide car bomb exploded in a village near the Abu Ghraib area on the capital's western outskirts, killing five and wounding six.
Northeast Baghdad's mixed Sunni-Shiite Qahira neighborhood was hit by a blast that shook the Faraj market, killing three people and wounding 12.
The nearby College of Fine Arts was also attacked by a car bomb that killed two more and wounded three others.
Security forces were targeted as well, with one bomb near an Iraqi army patrol killing a soldier and wounding four passers-by on east Baghdad's Palestine Street.
Three policemen were also wounded in a roadside bombing near central Baghdad's Al-Shaab stadium.
Mortars were fired, with nine rounds hitting the Sunni Adhamiyah district, killing three and wounding 11 and three hitting the Shiite Kadhimiyah district, wounding 15.
The flashpoint city of Baquba, northeast of the capital, reported 10 deaths in numerous incidents.
Deep in the south of the country, meanwhile, one civilian was killed and another three wounded when a bomb exploded near their car northeast of the city of Amara, a security offical said.
