An investigation by the BBC has found that 80 per cent of advertisements on two websites used by landlords say people on benefits will not be considered as tenants.
The sites are SpareRoom and OpenRent - and both have told the BBC they are addressing the issue.
By contrast less than one per cent of the rental advertisements on Zoopla and Rightmove had similar problems.
In the summer a court ruling determined that blanket bans on benefit claimants contravened the 2010 Equality Act.
The BBC analysed 59,000 listings on SpareRoom and OpenRent.
“Both platforms currently offer landlords a tick-box option to exclude people on benefits, although SpareRoom plans to remove the option” says the corporation.
OpenRent founder Adam Hyslop tells the BBC: "We know that access to suitable properties for benefit claimants is a real and painful problem, and we want to solve the root causes of these issues.
"We've raised these issues in Parliament and with industry lobby groups and are working hard to address the root causes - as well as trying to combat prejudice by educating OpenRent users.
"OpenRent does not ban any group of tenants, and in the past year we have let over 25,000 properties where applications from benefit claimants were explicitly welcomed by the landlord."
And SpareRoom director Matt Hutchinson says: “After the July ruling we changed the way SpareRoom works, so landlords can only list rooms as unavailable to benefit claimants if their mortgage or insurance specifically forbid it. However, we've seen far more rooms still being listed as unavailable than the small number we expected.
"The reality is that there are almost no buy to let mortgages left with those clauses in them, so we're currently in the process of removing the option to list as unavailable to benefit claimants completely."
You can see the full BBC story here.