The number of houses sold in August has increased by more than 16% compared with the same month in 2011.
The Real Estate Institute says more than 6035 properties sold in August, 843 more than the previous year.
The median house sale price also rose 4.2% to $370,000, just below June's record high of $372,000.
The institute's spokesperson, Helen O'Sullivan, says sales normally dip at this time of the year.
Ms O'Sullivan says the increased activity is being driven by house buyers in Auckland, while other parts of the country remain subdued.
She expects the upward trend will continue.
