Police officials said a suicide bomber drove his explosives-laden car into an army checkpoint in the town of Youssifiyah, killing 11 people, including four soldiers, and wounding at least 24 people.
Several cars were burnt in the attack.
Youssifiyah is 20 kilometers (12 miles) south of Baghdad.
Hours later, a roadside bomb targeting an army patrol killed two soldiers and wounded five others in Latifiyah, a town 30 kilometers (20 miles) south of Baghdad.
Medical officials confirmed the casualty figures. All officials spoke on condition of anonymity as they were not authorised to speak to the media.