The first car bomb exploded in a garage under a wholesale market in the Shorja district killing more than 40 people.
A second explosion hit the Haraj market just over one kilometre away, killing at least five more people and wounding more than 30.
People on fire
A column of smoke hundreds of feet wide billowed into the air above the market near the east bank of the Tigris river and near the Central Bank building.
Ambulances and trucks took the wounded to nearby al-Kindi hospital in the largely Shia region that has been hit by a series of deadly bombings since the first of the year.
A cameraman at the scene saw people on fire and more than 30 ambulances arriving.
The two car bombs, which occurred within 100m of each other, collapsed a building and set shops and market stalls on fire.
The Samarra attack by al-Qaeda in Iraq in 2006 set off a torrent of sectarian bloodletting that has turned Baghdad and much of central Iraq into a battleground.