The attacks came as Iraqi Shiites were celebrating the birthday of Imam Ali, the cousin and son-in-law of the Prophet Muhammad and Shiite Islam's most sacred martyr.
Police officials said a car bomb went off in the Baghdad neighbourhood of Sadr city, killing four people and wounding six in the morning hours.
Another car bomb elsewhere in Sadr city went off near a cluster of homes, killing two people and wounding seven. Associated Press Television footage from one of the Sadr city attacks showed a thick smoke rising from the blast area where several cars were von fire.
A short while later, a car bomb exploded in a commercial street in Baghdad's eastern district of Jamila, killing three people and wounding 10.
Police said a fourth car bomb went off near a traffic police office in eastern Baghdad, killing three people, including a traffic policeman. Seven people were wounded in that attack.
A car bomb explosion at a square in downtown Baghdad killed two people and wounded eight, said police. Yet another car bomb went off in a commercial street in Baghdad's Shiite eastern district of Ur, killing five people and wounding 11.
Medical officials confirmed the casualty figures. All officials spoke on condition of anonymity because they were not authorised to talk to media.
According to the United Nations, 8,868 people were killed in Iraq last year -- the country's highest death toll since the peak of sectarian bloodletting in 2007 and 2008.