Barnsley Warren (grid reference SP055064) is a 61.3-hectare (151-acre) biological Site of Special Scientific Interest in Gloucestershire, notified in 1954 and renotified in 1984. The site is also a Nature Conservation Review site. It lies in a steep-sided dry valley, east of the A429, northeast of Cirencester in the Cotswolds. The site is listed in the 'Cotswold District' Local Plan 2001-2011 (on line) as a Key Wildlife Site (KWS). Following the introduction of the Countryside and Rights of Way Act, the whole of the site was designated "access land" and is therefore open to public access.