Rannoch Moor (/ˈrænəx/ ; Scottish Gaelic: Mòinteach Rai(th)neach) is an expanse of around 50 square miles (130 km) of boggy moorland to the west of Loch Rannoch in Scotland, from where it extends into westerly Perth and Kinross, northerly Lochaber (in Highland), and the area of Highland Scotland toward its south-west, northern Argyll and Bute. Rannoch Moor is designated a Site of Special Scientific Interest (SSSI) and a Special Area of Conservation. Much of the western part of the moor lies within the Ben Nevis and Glen Coe National Scenic Area, one of 40 such areas in Scotland.
It is notable for its wildlife, and is particularly famous as being the sole British location for the Rannoch-rush, named after the moor. It was frequently visited by Horace Donisthorpe, who collected many unusual species of ants on the moor and surrounding hilly ground. Today it is still one of the few remaining habitats for Formica exsecta, the "narrow-headed ant", although recent surveys have failed to produce any sign of Formica pratensis, which Donisthorpe recorded in the area in the early part of the 20th century.