Harrow Weald Common is an 18-hectare area of woodland, heath and pasture in Harrow Weald in the London Borough of Harrow. It is considered of considerable importance for wildlife, and it was formerly part of the Stanmore and Harrow Weald Commons and Bentley Priory Site of Special Scientific Interest, but in 1987 the boundaries of the SSSI were revised to exclude the Common. It has been designated by the Mayor of London as a Site of Metropolitan Importance for Nature Conservation.