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In the run up to the general election on 7 May 2015, various organisations carried out opinion polling to gauge voting intention. Results of such polls are displayed in this article. Most of the polling companies listed are members of the British Polling Council (BPC) and abide by its disclosure rules.

The date range for these opinion polls is from 6 May 2010 (the date of the previous general election) to 7 May 2015.

Most opinion polls cover only Great Britain (England, Scotland and Wales). Separate polls covering constituent countries of the UK and English regions are reported further below while polling of individual constituencies and groups of them (such as groups of marginals) is covered in a separate article.

In the event, the actual results proved to be rather different from those indicated by the opinion polls. Opinion polls conducted in the last few months of the campaign, and even in the last few days, had indicated a very close result between the Conservatives and Labour in terms of numbers of votes, suggesting that one of the main parties would have to form a perhaps complex coalition with smaller parties in order to govern.

However the actual results showed a stronger performance by the Conservatives, which gave them an overall majority, since Labour also had a weaker performance than the polls had suggested.^[1][2][3] When the exit poll was initially presented, some commentators and politicians doubted it, with Paddy Ashdown even declaring "If this poll is correct I will publicly eat my hat on your programme" in response to the apparently poor results for the Liberal Democrats.^[4] The exit poll was eventually proved to have in fact overestimated the Liberal Democrats' performance. If the Survation telephone poll (6 May) had been published it would have produced results within 1% of the election results.

The chart shows the relative state of the parties from 13 May 2010 to 7 May 2015, with each line's colour corresponding to a political party: red for the Labour Party, blue for the Conservative Party, purple for the UK Independence Party, yellow for the Liberal Democrats, and green for the combined Green Party of England and Wales and Scottish Green Party. While not shown here, other parties have on occasion polled higher than one or more of the parties represented, for example in the Lord Ashcroft poll conducted on 17–19 April 2015, where the Scottish National Party polled 6% and the Greens 4%.^[5] Each dot represents a party's results from an opinion poll displayed in the table below.

Poll results are listed in the table below in reverse chronological order.^[6] The highest percentage figure in each polling survey is displayed in bold, and the background shaded in the leading party's colour. The 'party lead' column shows the percentage-point difference between the two parties with the highest figures. In the instance of a tie, no figure is shaded but both are displayed in bold.

Throughout the 2010-2015 parliament, first and second places have without exception alternated between the Conservatives and Labour. The Liberal Democrats and the UK Independence Party have tended to hold either third or fourth place in each individual poll. The combined Green parties of England and Wales and Scotland have most frequently polled fifth and have on occasions polled fourth – level with or ahead of the UK Independence Party or the Liberal Democrats. Included in the 'others' column are other smaller parties, the largest of which (by votes at the 2010 general election) are the British National Party, the Scottish National Party and Plaid Cymru. Detailed poll results that break down 'others' for some dates in 2014 and 2010 are available in a second table, below.