According to the findings, the 'average' Australian house is on the market for 77 days, and units for 51 days.
The poor results highlight the deterioration in the market as time on market for a house has increased by 64 per cent over the past two years. In 2010, it took 47 days to sell a house, RP Data said.
The sale time for units rose 34 per cent in the same two year period, with 2010 results showing they took an average of 38 days to sell.
RP Data also found sellers were discounting their asking prices by about seven per cent across the board compared with a year ago for both houses and units.
"The ongoing weakness in the housing market is likely to result in vendor discounting and time on the market remaining at above-average levels," RP Data research analyst Cameron Kusher said.
However, he said having fewer properties on the market may help improve the situation.
"In recent months, the amount of stock has declined and the volume of sales has stabilised, which may result in further improvements in vendor discounting and time on market," Mr Kusher said.
This was largely consistent with data from the most recent Real Estate Business Quarterly Sentiment Poll, which found that 65 per cent of respondents expected their days on market to either decline (21 per cent) or remain static (44 per cent) in the second quarter.
Furthermore, just under half of the respondents (49.8 per cent) said they had given vendors a discount in the first three months of this year, even though 75 per cent were asked to do so.
Recent figures released by SQM Research revealed that residential listings declined during the month of April 2012, decreasing by 4.2 per cent from March and coming to a national total of 371,470.