About 12,000 children in the North West are homeless, according to the housing charity Shelter.
Shelter says homelessness is a big problem in the region
The charity said it was "alarmed" that a third of its clients in the region during 2002 were families with children, more than half of whom were homeless.
The highest proportion of homeless families was in Greater Manchester where 54% of families seen were affected.
The charity is calling on the government to stop using bed and breakfast hotels as temporary housing by March 2004.
It says frequent moves from temporary accommodation have a negative effect on children, forcing them to change schools and making it hard for them to maintain friends.
Many live in damp and cramped conditions which can lead to respiratory and stomach illnesses and an increased chance of accidents.
Percentage of families seen by Shelter which are homeless
Cheshire - 48
Greater Manchester - 54
Lancashire - 49
Merseyside - 51
Poor living conditions, the charity says, also often lead to emotional and behavioural problems among youngsters.
Adam Sampson, director of Shelter, said: "Shelter sees thousands of families with children every year who are experiencing the terrible hardship of bad housing and homelessness.
"These families are living at the sharp end of the housing crisis."
Shelter hopes to raise £1m through its role as the official charity of the London Marathon, which is being held on 13 April.