Mintel, which conducted today's research, says two million UK residents own more than one house either in Britain or abroad, set against the backdrop of first-time buyers struggling to get a foothold on the property ladder.
"It is clear that these days, buy-to-let is no longer the exclusive domain of professional portfolio landlords," said Mintel's Paul Davies.
The senior financial analyst explained that the rise of buy-to-let could be explained by one third of respondents viewing property investment as "better" than traditional pension provisions.
"Increasingly, property owners are seeing the benefits of investing in bricks and mortar and often regard the second homes market as a good alternative means of saving for retirement," he said.
"As long as these trends continue, future growth in this market should be guaranteed."
Mintel's research forecasts that by the end of the year, 361,000 buy-to-let mortgages will have been taken out in the UK, rising to 550,000 by 2011.
"The buy-to-let mortgage market has experienced meteoric growth since the late 1990s, outperforming the wider mortgage market over the past few years," Mr Davies continued.
"Mintel expects the market to continue to grow at a healthy rate over the coming years, driven by the expected expansion in the population and the continuing strong demand for rented accommodation."
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