A suicide bomber detonated a pick-up truck on Wednesday in Sadr City, a heavily-populated Shia suburb of Baghdad, killing at least 15 and wounding 50, Iraqi security sources have said.
The explosion, the deadliest in Baghdad so far this year, targeted a crowded street full of garages and used-car dealers.
Although no one has claimed responsibility for the attack, Islamic State have been responsible for similar bombings in the past.
The group has stepped up bombings in Iraq last year, in retaliation for a US-backed campaign that dislodged the hardline Sunni group from most of the Iraqi cities it took over in 2014.
The militants also control parts of neighbouring Syria.