A total of 38 suspected Isis fighters in Nasiriyah in southern Iraq have been executed on charges of terrorism, the justice ministry has said.
The deaths on Thursday mark the largest number of executions in a single day since 25 September, when 42 people were put to death in the same prison on charges ranging from killing members of the security forces to making car bombs.
Tens of thousands of people are currently being held in Iraqi jails accused of affiliations with the extremist organisation.
Prime Minister Haider al Abadi formally announced the US-backed Iraqi coalition had defeated the jihadists - who blitzed across the country from neighbouring Syria in 2014 - last week.
Under Iraqi law, being found guilty of being a member of Isis carries a sentence of life imprisonment or death.
Human Rights Watch warned earlier this month that the mass trials of Isis fighters seen in recent months are rife with due diligence violations.
All appeal options available to the condemned had been exhausted, according to the statement.
Processing suspected fighters is expected to clog up the Iraqi justice system and prisons for years to come.