A Department of Labour study shows the proportion of the population leaving permanently for Australia was near an historic low in 2011.
That's despite the actual number crossing the Tasman reaching a record high.
Research head Vasantha Krishnan says more people left for Australia last year than arrived from Australia to live here than at any time since 1979.
But she says population growth puts that in a different perspective.
Radio New Zealand's economics correspondent says permanent departures for Australia exceeded those arriving from across the Tasman to live here permanently by 45,000 during 2011.
The last time the exodus was as high was in 1979 when net departures totalled 44,000.
According to the department, the net numbers leaving last year accounted for 1% of New Zealand's population, a near historic low.
The department is forecasting a continued rise in the actual number of New Zealanders leaving for Australia, before easing late this year.