Perth house prices are in freefall after a fourth consecutive quarterly fall in the median price - something not seen in 25 years - but renters are yet to see any benefit.

Real Estate Institute of WA president Rob Druitt said rents had continued to increase due to a shortage of rental properties, but he predicted the sting would end as the vacancy rate grew.

'We expect rents to now level out or even start to peg back,' Druitt said yesterday.

With the median Perth house price plummeting 12 per cent in 2008, Mr Druitt said buying a home was more affordable for renters who had been priced out of the market for years.

The Australian