Warburg Nature Reserve is a nature reserve and site of special scientific interest in Oxfordshire, England that is owned and managed by the Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust. It is located in the Chiltern Hills area of outstanding natural beauty in the Bix valley, 4 miles northwest of Henley-on-Thames. The name commemorates Oxford botanist Dr. E. F. Warburg, a founder member of the Trust.
The reserve is composed mainly of chalk grassland and ancient woodland and it includes a visitors centre, a picnic area and two bird hides. Species include birds and butterflies and over 2,000 species of plants, fungi and animals have been recorded there.