New Zealand would have a new flag if it were up to six of its 71 electorates.
A majority of voters in Bay of Plenty (51.4 per cent), Clutha-Southland (50.4 per cent), East Coast Bays (51.1 per cent), Ilam (50.8 per cent), Selwyn (51.7 per cent) and Tamaki (51.9 per cent) opted for a new flag, according to preliminary results.
All of those areas are held by National MPs.
In Prime Minister John Key's Helensville electorate, 56.6 per cent of people chose to keep the current flag.
Support for the current flag was strongest in Maori electorates, including Te Tai Tokerau (78.5 per cent) and Tamaki Makaurau (77.5 per cent).
Other areas strongly in favour of keeping the current flag included Mangere (70.8 per cent), and Manukau East (67.4 per cent).
Voter turnout across New Zealand's 71 electorates ranged from 78.7 per cent in Selwyn, to 41.1 per cent in Manukau East.
Across New Zealand, total voter turnout was 67.3 per cent in the preliminary results announced tonight.
Turnout is calculated by taking the total votes received as a percentage of the total number of voters enrolled as at 19 November 2015 (3,170,726).