The packages were reportedly sent to the offices of three Conservative Member of the Scottish Parliament (MSP).
The packages, at least one of which contained white powder, had been sent to Tory MSPs Liz Smith, Edward Mountain and Jamie Halcro-Johnston.
Police and firefighters have been called to the scene and MSPs have evacuated the legislature.
The Scottish Parliament is the devolved national, single-chamber legislature of Scotland, located in the Holyrood area of the capital city, Edinburgh.
The incident follows a series of terror attacks in London and Manchester this year, which prompted authorities to set the terrorist threat level at “severe,” indicating an attack is highly likely.