Amersham is a market town and civil parish within the Unitary Authority of Buckinghamshire, England, in the Chiltern Hills, 27 miles (43 km) northwest of central London, 15 miles (24 km) from Aylesbury and 9 miles (14 km) from High Wycombe. Amersham is part of the London commuter belt.

There are two distinct areas:

• Old Amersham, set in the valley of the River Misbourne, containing the 13th-century parish church of St. Mary's and several old pubs and coaching inns
• Amersham-on-the-Hill, that grew in the early 20th century around the Metropolitan Railway - later the Metropolitan line of the London Underground.

The name Amersham is derived from the Old English for 'Ealhmund's village (ham)'.

Records date back to pre-Anglo-Saxon times when it was known as Agmodesham, and by the time that the Domesday Book was written around 1086 it had become known as Elmodesham.

Amersham station is a terminus of London Underground's Metropolitan line. Much of this route is shared with the mainline railway from Marylebone to Aylesbury. Before electrification, the Metropolitan line ran via Aylesbury to Verney Junction and Brill. London Transport abandoned plans to electrify beyond Amersham and the stations and line were sold to British Railways on 11 September 1961. To this day, these Chiltern Railways stations display a characteristic Metropolitan line architecture.