More than 80,000 people have fled west Mosul since the battle to retake the area began last month, the International Organization for Migration said on Tuesday.
Iraqi forces launched a major push to retake west Mosul -- the most populated urban area still held by the ISIS -- on February 19.
The IOM began recording displacements from the area six days later, and 80,568 people have fled since then, it said on its official Twitter account.
But that is still a small fraction of the 750,000 people who were estimated to still reside in west Mosul at the time the operation began.
ISIS overran large areas north and west of Baghdad in 2014, but Iraqi forces backed by US-led air strikes have since retaken most of the territory they lost.
Iraqi forces launched the operation to recapture Mosul from ISIS in October, retaking its east before setting their sights on its smaller but more densely-populated west.
According to the IOM, more than 238,000 people are currently displaced due to fighting in the Mosul area, while more fled but later returned to their homes.