Many have shaved off their beards and mustaches and slapped on make-up. Some are even pictured wearing silk bras and dresses beneath their burkas.Arabic captions suggest the pictures were taken in the Baiji area of northern Iraq.
Regular Iraqi forces have fought an almost continuous battle around an important oil refinery there, backed up by US-led air strikes.
Some of the captured ISIS escapees are seen being accompanied by senior ranking officers from the official Iraqi army.
The Instagram account also carries gruesome images of dead ISIS fighters and shows pictures of a poster boy on the front line fighting insurgents.
Abu Azrael – nicknamed the Angel of Death – is a commander with the the Imam Ali brigade, an Iraqi Shi’a militia group sponsored by Iran. He is believed to be a 40-year-old former university lecturer who left his home to fight ISIS last June.
Pictures show the bald fighter in his military fatigues, posing with an axe and a heavy machine gun.