St. Catherine's Valley (grid reference ST760725) is a 156.1-hectare (386-acre) biological Site of Special Scientific Interest (SSSI) located southwest of the village of Marshfield, in South Gloucestershire, England. It was notified as an SSSI in 1997.
The valley lies within the area of search for Avon. At the Marshfield end of the valley, a large naturalised population of Dragon's Teeth (Tetragonolobus maritimus), a species not native to Britain, is present. This population was first recorded by Rev. E. Ellman in 1927.
The valley is also situated near the dispersed settlement and civil parish of St Catherine, Somerset, which lies north of Batheaston and northeast of the city of Bath. Approximately 1 mile (2 km) up the valley from St Catherine are two Sites of Special Scientific Interest: St. Catherine's Valley and Monkswood Valley. The area is part of the Cotswolds region and is known for its rolling fields, country paths, and scenic landscapes.
