At least 33 people were killed and 48 wounded in a car bomb attack on a busy square in Baghdad's sprawling Sadr City district, police and medical sources said.
There was no immediate claim of responsibility for Monday's attack but the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group regularly targets civilian areas in the heavily fortified capital.
Three bombs killed 29 people across the city on Saturday. An attack near the southern city of Najaf on Sunday left seven policemen dead.
US-backed Iraqi forces are currently fighting to push ISIL fighters from the northern city of Mosul, the armed group's last major stronghold in the country, but are facing fierce resistance.
Since the offensive began on October 17, elite forces have retaken a quarter of the city in the biggest ground operation in Iraq since the 2003 US-led invasion that toppled Saddam Hussein.
As clashes continued in and around Mosul on Monday, ISIL also targeted military positions away from the main battlefield.
Fighters attacked an army barracks near Baiji, 180 km (112 miles) north of Baghdad, killing four soldiers and wounding 12 people, including Sunni tribal fighters, army and police sources said.
They seized weapons there and launched mortars at nearby Shirqat, forcing security forces to impose a curfew and close schools and offices in the town, according to local officials and security sources.
Shirqat mayor Ali Dodah said ISIL seized three checkpoints on the main road linking Baiji to Shirqat following the attacks. Shelling in Shirqat had killed at least two children, he told Reuters by phone.
In a separate incident, gunmen broke into a village near Udhaim, 90 km (56 miles) north of Baghdad, where they executed nine Sunni tribal fighters with shots to the head, police and medical sources said.
At least three pro-government Shia militia were also killed and seven wounded when fighters attacked their position near Udhaim with mortar rounds and machine guns, police sources said.
Prime Minister Haider al-Abadi has said the group would be driven out of the country by April.