More than 20,000 houses, accounting for nearly half of homes sold last year, were cash transactions, according to property website MyHome.ie.
Angela Keegan, the website's managing director, said this level of cash transactions was not sustainable in the long-term.
"The property price register shows that 42,484 houses were sold last year. According to the Banking and Payments Federation Ireland, 22,119 mortgages to the value of €3.9 billion were drawn down during the year.
“This means the remainder, 20,365, were bought for cash. While it was thought the number of cash buyers was declining, this shows there is still a lot of cash out there and a lot of it is finding its way into property.”
Ms Keegan said there had been a significant increase in the number of house sales this year. The property price register showed 2,904 sales had been recorded nationally compared to 1,924 in January of last year. In Dublin there have been 1,117 sales so far, a rise of 85 per cent on last year.