While the institute described house prices as "stable" across the country, the sales figures it provided show Southland to be an exception.
In Southland in November, 123 houses were sold at a median price of $165,000.
A month earlier, 132 houses sold at a median price of $198,500.
The difference is $33,500 or 16%.
For the 12-month period, the median price in Southland has fallen by $44,025, or 21.06%, from $209,025 in November last year to this November's $165,000.
The number of sales in Southland in November (132) was less than half that of every November since 2001, except last year, when 226 houses were sold.
The median price for the 13 houses sold in Gore fell to $120,000 in November from $182,500 in October.
Real Estate Institute president, Mike Elford, acknowledged slow sales throughout the country which he considered could be put down to a combination of the election, the state of the global economy and a "wait-and-see" approach from buyers.
"People are also watching for the effect of the interest-rate cuts to come into the equation."
Mr Elford said housing affordability was "the best it has been for a long time" but first-home buyers were facing stricter lending criteria.
Total dwelling sales, nationally, dropped by 190 - from 4469 in October to 4279 in November.
The national median house price for November was $337,500, up $2500 on October's $335,000.
Compared with the corresponding month last year, November's median price was down $14,500 which represents a 4.11% decline.
The Central Otago-Lakes region had the largest gain across the country during the 12 months, the median house price rising 10.46% from $430,000 last November to $475,000 this November.
However, there was no change between October and November.
The number of sales for November, at 69, was down 10 on October and down 51 on November last year.
The Otago region experienced a $12,000, or 5.1%, decline in the median price from $235,000 in November last year to $223,000 this year.
Between October and November, the decline was $7000.
The number of sales for November was 203, up two on October but down 67 on November last year.
Mr Elford said: "The message I am hearing frequently is that there continues to be strong demand for well priced stock."