Sales to first-time buyers collapsed by over a quarter in the year to June.
The claim comes this morning from agents Reeds Rains and Your Move, both LSL firms.
According to figures based on its own data, it estimates that in June there were 21,000 first-time buyer transactions at an average price of £154,910.
The number is down 7% on the month, by 8.3% on the quarter, and by 27.2% over the year.
The average purchase price, however, was unchanged from June 2014.
The average deposit was also almost unchanged from June last year, at just under £26,000.
In London the average purchase price for a first-time buyer in June was £277,871, requiring a deposit of £70,374.
Lack of cash for a deposit was the biggest single reason cited by tenants for being unable to buy.
The two agents also asked tenants if they planned to get on to the housing ladder by the end of this year: just 8% said yes, down from 16% a year ago.
Asked what sacrifices they might make in their first home, the potential first-time buyers said they would put up with dated décor and bathrooms, and some said they even go without basic utilities such as electricity and plumbing if necessary.
Almost half, 45%, said they would accept a property of any condition, as long as it was within their budget.