The 'no' case is ahead in NSW, Tasmania and Victoria as the first votes in the Indigenous referendum are counted.
The three states were considered to be among the best prospects for the 'yes' campaign.
At 6.30pm AEDT, Australian Electoral Commission figures showed 63 per cent 'no' and 37 per cent 'yes' across the three states and the ACT where counting had started.
Victoria was recording the strongest 'no' vote at 68 per cent, while 62 per cent of NSW voters backed 'no'.
Tasmanians voted 65 per cent 'no' and 35 per cent 'yes'.
The ACT was the only jurisdiction where the 'yes' vote was ahead.
In the national capital, 75 per cent voted 'yes' and 25 per cent voted 'no.