Only 23 dwellings - 20 houses and three apartments - were sold in May, a number Queenstown Real Estate Institute of New Zealand spokesman Adrian Snow described as "abnormally low".
It was the lowest monthly sales figure since December 2000, even though May and June were traditionally quieter sales months.
"May's activity was unexpected among realtors, but the reality is that even though we are generally perceiving increasing confidence and increasing stability, there is still the occasional off-month to be experienced through the economic recovery period."
Thirteen sections were sold during the months, bringing the total number of sales to 36.
That was just over half the 65 sales in April this year, and 18 fewer than the total for May last year.
The median selling price for houses and apartments rose from $470,000 in April to $570,000 in May.
The sale of six properties for more than $1 million each had pulled the median price up, Mr Snow said.
Dwelling sales were also down in Dunedin city - 154 compared to 175 in April and 164 in May last year.
The median price in Dunedin City dropped from $248,000 in April to $241,2500 in May but was up on the May 2009 median of $235,000.
Central Otago Lakes house sales totalled 44, down on the 53 sold in April but five more than the 39 sold in May last year.
From April's $370,00, the median price for property in Central Otago decreased to $355,000 in May.
The median price in May last year was $399,000.
In North Otago, 25 properties were sold, marginally up on the 23 sold in April but 10 fewer than the 35 sold in May last year.
The May median sale price rose to $222,000 from $170,000 in April and was also up on the May 2009 median of $190,000.
Sales declined in Gore, with 23 dwellings sold in May compared to 28 in April.
However, only 18 homes were sold in the town in May last year.
The median price decreased from $155,100 in April to $140,000 in May and was also down on the median of $170,000 a year ago.
Nationally, sales figures and prices remained steady, REINZ president Peter McDonald said.
The median residential property price eased back to $350,000 from $356,000 in April, while the property sales total of 5206 was only one less than the 5207 sold in April.
While there had been some decline in turnover from the boom times of two years, almost 67,000 homes had been sold for a total of almost $27.5 billion in the 12 months to the end of May, Mr McDonald said.
