Police say the first bomb went off after prayers today as worshippers were leaving the Ali Bin Abi Talib mosque in Baghdad's western Shurta district.
Seconds later, a second bomb exploded among worshippers trying to flee the scene of the attack.
A hospital official confirmed the casualties. All officials spoke on condition of anonymity because they were not authorised to speak to reporters.
Today's violence comes a day after bombings killed 30 people across Iraq.
Attacks on mosques, especially Sunni ones, have increased recently. While it's possible Sunni insurgents seeking to stoke sectarian hatred could be to blame for them, Shiite militias may also be behind the assaults.