A wreath-laying and church service will be held in the south of Scotland town which was devastated when Pan Am flight 103 was blown from the skies in 1988.
Events will also take place in London and near Washington DC.
It emerged on Friday that the family of Lockerbie bomber Abdelbaset Al-Megrahi want to appeal against his conviction.
Among the gatherings marking the anniversary of Britain's worst-ever terrorist attack is a remembrance service being staged at Westminster Abbey in London.
In the US, a ceremony will take place at the memorial cairn in Arlington National Cemetery, near Washington DC.
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