The Real Estate Institute says there is not enough evidence to know the impact of migration on the housing market in Auckland.
In the Budget, the Treasury forecast higher immigrant numbers for the year than expected and said that could hamper efforts to rein in house prices.
Treasury expects the annual net inflow of migrants will peak at 38,000 in the second half of this year.
An earlier forecast was 26,000.
Institute chief executive Helen O'Sullivan told Morning Report most of what is known on the topic is anecdotal.
