The Free Church of Scotland has voted to relax its rules to allow hymn singing and the use of instruments in its churches.
A plenary assembly gathered in Edinburgh to rule on the change.
Unaccompanied psalm singing is currently the only music permitted in public worship by the Free Church.
The vote ended with the commissioners of the church, splitting 98 to 84, with a majority of just 14 in favour of allowing hymns and instruments.
Conservatives called for a vote on whether they should consult the wider church membership through the presbyteries before the rules were changed.
The church split as recently as 2000 over doctrine and observers have said it is not impossible that it could happen again.
A plenary session last took place when the Free Church split from the Church of Scotland in 1843.
Ministers who supported the change believe it could attract new worshippers to congregations suffering from declining membership.
But traditionalists fear it could damage the unity of the church.
The Reverend David Robertson, minister of St Peter's Free Church in Dundee and editor of The Record monthly magazine, has said traditional psalms would not be sacrificed if music and hymns were introduced.
A Church Board of Trustees report recommended maintaining the status quo.
Live updates from the plenary session are being posted on the church's website.
The Free Church was formed after more than 450 ministers walked out of the Church of Scotland general assembly in a row over the process of appointing ministers.
They wanted the right to veto ministers put into churches by "the patron", usually a local laird, establishing the Free Church in 1843.