First-time buyers account for less than a quarter of all house purchasers and in many areas on the UK account for a fifth or even fewer.
Rightmove said that at just 22.8%, the proportion of first-time buyers is now around half the level typical of a healthy housing market.
More than half said their biggest concern was getting a mortgage, with 44% saying their main concern was raising a deposit. A further 10% were worried about being able to meet monthly mortgage payments.
The findings were discussed at yesterday's emergency summit, held by housing minister Grant Shapps to discuss the first-time buyer crisis. The meeting heard that there is no 'magic bullet' to solve the problem.
Rightmove questioned nearly 30,000 prospective home buyers last month. Of this number, less than one in four said they were planning to buy for the first time.
But the 22.8% proportion is a national average, boosted by the much higher number (at 38.6%) of prospective first-time buyers in London.
In Wales, the proportion falls to 18.4%, and in the south-west to 18.7%. In Scotland, the proportion of first-time buyers is just 19.9%, in East Anglia it is 19.6%, in the north 20.5% and in the south-east 21.6%.
Rightmove has been tracking first-time buyers’ intentions since the last quarter of 2009, when 27.6% of respondents said they would be purchasing for the first time.
Miles Shipside, director of Rightmove, said: “The level of first-time buyers dropping below one in four of all prospective buyers is a big concern for the property market.
“The desirable level of first-time buyers for a healthy market is typically around 40% of all buyers, almost double the current level, as they perform a vital function in completing chains and aiding fluidity throughout the housing ladder.
“These findings are likely to heighten Government concerns about the scarcity of first-time buyers and it is imperative for the long-term health of the market that a solution to this issue is found.”