Perth's median house price has taken its biggest tumble in nearly two years, according to the latest data from the Real Estate Institute of Western Australia (REIWA).

Figures show the median house price fell by $20,000 or 3.6 per cent in the June quarter to $530,000.

The median price for Perth units, villas, apartments and townhouses also fell from $440,000 to $420,000.

In regional WA, the median house price fell $10,000 to $380,000, while apartments dropped by about $4,500 to $325,000.

REIWA President David Airey said the fall in Perth's house price was much larger than expected.

"We knew prices were under pressure but, certainly across the real estate business, no-one expected the drop would be this significant," he said.

"That clearly shows that, with the big drop in the number of sales, there's got to be some consumer sentiment around that and I suspect in Western Australia it's very much to do with our poor, slow economy in the local market."

Mr Airey said the results likely indicated a fall in the price of more expensive homes, while cheaper properties in Perth were continuing to get good returns.

Properties were on the market for an average of 71 days in the last quarter, compared to 58 days 12 to 18 months ago.

"Currently people are sitting on their money, they're sitting on their hands, they're not rushing out to buy real estate as quickly as we'd like them to," Mr Airey said.

Government blamed for drop-off in first home-owners

In addition to a slowing economy and declining population growth, Mr Airey said a lack of interest from first home buyers was a factor in the price fall.

The data shows the number of people buying their first home was down by 1,000 or 21 per cent in the last quarter, which Mr Airey described as disturbing.

"As a result, the median purchase price for first home buyers has actually dropped by $20,000 down to $430,000 on the same time last year," he said.

"We warned the State Government that when they cut off the final $3,000 of the established home grant for first home buyers ... we said this will really slow the market down and it will actually affect ongoing established home sales."

Mr Airey said fewer sales would see less income for the government.

"We'd estimate the hit to stamp duty revenue is probably over $200 million and all the government could have possibly saved in removing that grant is around $30 million," he said.

He said first home buyers were vital to the success of any property market.

"We need to be encouraging them to buy and they need an incentive to buy," Mr Airey said.

"A $10,000 subsidy to new homes is not helping the West Australian economy."

The price tumbles continued in Perth's rental market, where the median price dropped $10 to $420 a week.

Prospective tenants were also spoilt for choice with more than 8,100 rental properties sitting empty, representing a vacancy rate of about 5 per cent.

"This means the overall median rent has now dropped by $55 over the last two years," Mr Airey said.

He expected the completion of new apartment buildings to see even more rental properties come on board in the near future; however, he also expected rental prices to stabilise.

As for people wanting to put their home on the market, Mr Airey urged sellers to focus on presentation and ensure the property was correctly priced.