Twelve car bombs and a roadside bomb struck different commercial areas in Baghdad’s predominantly Shia districts on Saturday.
At least 65 people died and about 200 others were wounded as blasts went off after the breaking of the daily Ramadan fast or Iftar.
In the deadliest attacks, two car bombs claimed the lives of 12 people in Karrada, central Baghdad, while two car explosions and a roadside bomb hit Zafraniyah, southwest Baghdad.
Earlier in the day, gunmen shot and killed Bassem Mahmoud, a leader of the anti-al-Qaeda group Sahwa, and two of his bodyguards near the city of Baqouba, the capital of Diyala Province.
Meanwhile, a bomb blast in Madain, about 20 kilometers (14 miles) southeast of Baghdad, killed five people.
In the northern city of Mosul, an explosion killed one woman and wounded 25 others.
According to the UN, about 2,500 people have been killed in Iraq in the past three months.
Iraq has been experiencing a surge in deadly attacks since the beginning of the holy month of Ramadan in early July. Iraqi officials say the acts of violence are being committed as part of a foreign-backed plot to foment sectarian strife in the country.
Iraqi Prime Minister Nouri al-Maliki says militant groups and remnants of the ousted Baathist regime are responsible for the carnage.