The residential property market in New Zealand is healthy despite a decline in the median house price in May, with a modest annual growth rate indicating that the Reserve Bank's interest rate strategy is working, an economist says.

The median residential property price eased in May to $NZ350,000 ($A283,458) from $NZ356,000 ($A288,317) in April, and was still 3.7 per cent ahead of a year earlier, the Real Estate Institute of New Zealand (REINZ) said on Tuesday.

The figures showed no real reduction in residential property prices or the number of sales in May, despite pending tax changes and the anticipated move by the Reserve Bank of New Zealand (RBNZ) to raise interest rates as it did earlier this month, the institute said.

The 5206 residential property sales last month were only one fewer than in April, even though winter was usually a quieter period for the real estate market. The median number of days to sell rose to 43 from 40.

"The housing market is healthy and while prices are close to record highs, the modest annual rate of house price growth suggests the RBNZ's 'lower for longer' interest rate strategy has not created a speculative bubble," said TD Securities economist Roland Randall.

"In part, this is because New Zealand has recently been through recession and the unemployment rate spiked to 7.1 per cent.

"For now, New Zealanders are saving more and borrowing less," Mr Randall said.

The REINZ monthly housing price index fell by 1.4 per cent in May, with prices 5.1 per cent below their peak in November 2007.

The index, which basically is an average of sale prices for common groups, rose 0.7 per cent in the three months to May, and compared to a year earlier was up 2.3 per cent.

Tuesday's report follows QV figures last week which showed residential property prices 4.1 per cent below the market peak of late 2007, having been 3.9 per cent below the peak a month earlier.

QV indices showed values were 5.6 per cent above the same time last year, the first decline in the annual change since March 2009, having fallen back from the 6.1 per cent reported for April.

The market's reaction to tax changes in last month's government budget would not be obvious until July, Goldman Sachs JBWere economist Philip Borkin said.

"Nevertheless, we believe house price growth will continue to moderate over the remainder of this year and remain somewhat modest for the foreseeable future," he said.