A Panelbase survey found 52% of Scots are to vote for the union, with 48% favouring independence, when undecided voters are excluded.
The result is exactly the same as three separate polls which were published last night.
The Panelbase survey, which came out less that 24 hours before voting gets under way in the referendum, continues to suggest the campaign over the future of the UK could go down to the wire.
Exactly half (50%) of the 1,004 people who were questioned said they would be voting No to independence, with 45% voting Yes.
Just one in 20 (5%) of voters have still to make up their mind, according to the research.
Men continue to be more likely to support Scotland leaving the UK, with 54% of all males who were questioned said to be Yes voters, ahead of 44% who are voting No and 3% who are undecided.
Just under two-fifths (39%) of women questioned said they would be voting Yes tomorrow, with 54% backing No and 7% still undecided.