John Hampden Grammar School (known colloquially as "JHGS") is a 7–13 boys' selective state grammar school in High Wycombe, Buckinghamshire, England. It is named after the local member of parliament and English Civil War commander John Hampden. In June 2011, the school became an Academy.

Established as the Schools of Science and Art in 1893, it is situated on Marlow Hill to the south of the town and has a capacity of about 1,150 boys aged between 11 and 18.