Among the dead in the three separate attacks that followed Friday prayers was the Shiite imam of the al-Shorouq mosque in the northeast of the capital. Police say cleric Aref Majid was gunned down as he walked home after delivering his sermon.
Separately, another Shiite cleric has been seriously wounded and his driver killed in a drive-by-shooting in eastern Baghdad.
Also, gunmen have killed two Shiite worshippers as they were heading home after prayers in New Baghdad area in the capital's southeast.
Hospital officials have confirmed the casualties. All officials spoke anonymously because they were not authorized to release the information.
Insurgents frequently target Shiite pilgrims and worshippers in an attempt to reignite sectarian strife in Iraq.