West Yatton Down (grid reference ST852760) is a 14.4 hectare biological Site of Special Scientific Interest in Wiltshire, notified in 1971.
The site is an example of unimproved limestone grassland. Among the more notable plants species are Bastard-toadflax (Thesium humifusum), Dyer's Greenweed (Genista tinctoria), and Musk Orchid (Herminium monorchis). Other species present include Yellow-wort (Blackstonia perfoliata), Kidney-vetch (Anthyllis vulneraria), Devil's-bit Scabious (Succisa pratensis), Bee Orchid Ophrys apifera, Tor-grass (Brachypodium pinnatum) and Upright Brome (Bromus erectus).
The site is also of interest for invertebrates. 25 butterfly species have been recorded, including Chalkhill Blue, Duke of Burgundy, Pearl-bordered Fritillary and Green Hairstreak.
Coordinates: 51°28′58″N 2°12′52″W / 51.48276°N 2.21452°W