The SNP's Nicola Sturgeon, Scottish Labour's Jim Murphy, Scottish Conservative leader Ruth Davidson and Liberal Democrat Willie Rennie will take part in the BBC1 programme.
BBC political correspondent Glenn Campbell will chair the debate at 19:30.
It will be held in Edinburgh just four days before the country goes to the polls.
During the day the parties will continue their campaigning around the country.
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The general election takes place on 7 May.
To find out who is standing in your area, check out the BBC's constituency profiles.
You can watch the Leaders' Debate at 19:30 on BBC1 Scotland or on iPlayer.
Scotland's four main party leaders are preparing for a live debate later.