The sentences were carried out in Tehran's Evin prison, state television reported.
The condemned were said to have committed rape, murder with torture, armed robbery and the trafficking of hundreds of kilograms of narcotics, though some were also accused of drinking alcohol and possession of ammunition.
"These people had criminal records and were repeat offenders. Each time after serving a prison term, they were released only to return to drug trafficking gangs and to continue committing crimes," said Saeed Mortazavi, the chief prosecutor. "We are hoping Tehran will become the most unsafe place for drug dealers, thugs and trouble-makers and also violators of people's honour."
Amnesty International said that Iran executed 317 people last year - more than anywhere else except China. Some hangings were carried out in public.
Murder, rape, armed robbery, drug trafficking and adultery are all punishable by death under the country's sharia law, which has been enforced since the 1979 Islamic revolution.
However, following an outcry over the large number of public hangings, public executions were banned except in exceptional cases earlier this year by Iran's chief of judiciary, Ayatollah Mahmoud Hashemi Shahroudi.
The hangings are likely to intensify international scrutiny of Iran, which already faces heavy pressure to curb its nuclear programme or face heavier economic sanctions.
