The explosion near a maternity hospital occurred as the streets were packed with shoppers and people on their way to work.
The explosion also set at least 10 cars ablaze.
Al-Hillah, about 100 kilometers south of Baghdad, has been the site of some of the country's deadliest bombings, including a double suicide attack in March that killed 120 people.
Searching For A Way Forward
LOOKING BEYOND AL-MALIKI: RFE/RL Iraq analyst Kathleen Ridolfo led an RFE/RL briefing about the changing political landscape in Iraq, focusing on efforts to gain the upper hand in the event that the government of Prime Minister Nuri al-Maliki falls.
LISTENListen to the entire briefing (about 70 minutes):
Real Audio Windows Media