An estimated 1,000 people a day are returning across Iraq's borders having previously moved abroad to escape the violence, Iraqi authorities say.
Some of the returnees found it hard to make a living abroad
Most of the returnees are coming from Syria - and very few from Jordan, where better-off refugees tended to go.
An improving security situation - but also the lack of job opportunities for Iraqis in Syria - may account for the move, correspondents say.
However, at least five people died in a bombing in Ramadi on Wednesday.
A suicide bomber slammed a vehicle into a courthouse compound, police said.
The attack came as a sudden return to violence in a region which has become markedly more peaceful since Sunni tribesmen joined forces with the US military to tackle al-Qaeda militants last year.
Over 4.4m Iraqis are thought to have been displaced by violence since the US-led invasion of 2003 - but a growing trickle of those who fled the country are now coming back.
Iraq's ministry of migration told the BBC about 1,000 people were returning every day.
WHERE IRAQIS HAVE FLED TO
Gulf states: 200,000
Internally displaced: At least 2,000,000
Source: UNHCR (October 2007)
The UN's refugee agency, the UNHCR, estimates about 45,000 Iraqis returned from Syria in October - the first month of the school year.
One factor in their return is likely to be a sharp and sustained drop in all kinds of violence, particularly in parts of the capital Baghdad, following a US-Iraqi military "surge".
But the stream of returnees from Syria is not being matched by return traffic from Jordan, where there may be as many as a million Iraqi refugees.
That is probably because those in Syria are poorer, so their savings have run out more quickly, says the BBC's Jim Muir in Baghdad.
Syrian authorities, who have seen the country's population swollen by up to 10% by the flood of Iraqi refugees, have begun imposing visa requirements.
Iraqi authorities, for their part, have been providing incentives for refugees to return, such as free bus rides from Syria.
They have also tried to encourage those Iraqis displaced inside the country - who constitute about half the total - to return to their homes by offering families grants of $800 to do so.
So far 4,700 families have taken up the offer with another 8,500 registered for them.
But not all the returnees are confident the security improvement is permanent.
Watching decorators paint the home he has returned to in east Baghdad from Syria, retired policeman Abu Naseem told Reuters news agency: "After all this effort to fix the house I hope there will be no more fighting.
"But I think the violence will be back again."