Iranian state media say authorities have hanged 12 convicts in the southern city of Shiraz.
Media reports say seven of those executed were found guilty of drug trafficking.
Iran practices the Muslim Sharia law in which some serious crimes - including rape, armed robbery and kidnapping - are punishable by death.
Human rights groups charge that Iran is second only to China in numbers of people facing the death penalty. Iran dismisses criticism of its justice system.
Some information for this report was provided by AP and AFP.