Upper Winchendon or Over Winchendon is a village and civil parish in the Aylesbury Vale District of Buckinghamshire, England. It is about 1.5 miles (2.4 km) south of Waddesdon and 4.5 miles (7 km) west of Aylesbury. A mid-air collision between a plane and a helicopter just outside the village led to the Waddesdon Manor air incident on 17 November 2017.
The name "Winchendon" is derived from the Old English for "hill at a bend". Collectively the villages of Upper Winchendon and Nether Winchendon (or Lower Winchendon) were called Wichendone.