Hobart house prices are the nation's poorest performers.

The latest RP Data-Rismark Home Value Index survey reveals prices fell by 6.6 per cent in the three months to August and by more than 9 per cent over the past year.

The median dwelling price in Hobart is around $313,000, the lowest in the country and well down on the national average of $450,000.

RP-Data's Cameron Kusher says unit prices are even lower.

"Unit values fell 10.3 per cent compared to a 9 per cent fall in house values and that's a little bit different to what we're seeing across the other capital cities where we're seeing units are actually outperforming houses," he said.

The general slump in Tasmania's economy has been blamed for a dramatic fall in house prices.

Mr Kusher says with consumer and business confidence down, people are not committing large sums for housing.

"Really it just comes down to confidence.

"We've seen that all capital cities have recorded a fall in values over the last 12 months but Hobart, being the smallest capital, one of the smallest capitals and fairly isolated from the rest of Australia, I guess, is also impacting on that market as well."