Aylesbury, a market-town in the Aylesbury parliamentary division of Buckinghamshire, England, 38 m. N.W. by W. of London; served by the Great Central, Metropolitan and Great Western railways (which use a common station) and by a branch of the London & North-Western railway. Pop. of urban district (1901) 9243. It has connexion by a branch with the Grand Junction canal. It lies on a slight eminence in a fertile tract called the Vale of Aylesbury, which extends northward from the foot of the Chiltern Hills. Its streets are mostly narrow and irregular, but picturesque. The church of St Mary, a large cruciform building, is primarily Early English, but has numerous additions of later dates. The font is transitional Norman, a good example; and a small pre-Norman crypt remains beneath part of the church. There are some Decorated canopied tombs, and the chancel stalls are of the 15th century. The central tower is surmounted by an ornate clock-turret dating from the second half of the 17th century. The county-hall and town-hall, overlooking a broad market-place, are the principal public buildings. The grammar school was founded in 1611. Aylesbury is the assize town for the county, though Buckingham is the county town.

There is a large agricultural trade, the locality being especially noted for the rearing of ducks; straw-plaiting and the manufacture of condensed milk are carried on, and there are printing works. The Jacobean mansion of Hartwell in the neighbourhood of Aylesbury was the residence of the French king Louis XVIII. during his exile (1810-1814).

Aylesbury (aeylesburge, Eilesberia, Aillesbir) was famous in Saxon times as the supposed burial-place of St Osith. In A.D. 571 it was one of the towns captured by Cuthwulf, brother of Ceawlin, king of the Saxons. At the time of the Domesday survey the king owned the manor. In 1554, by a charter from Queen Mary, bestowed as a reward for fidelity during the rebellion of the duke of Northumberland, Aylesbury was constituted a free borough corporate, with a common council consisting of a bailiff, 10 aldermen and 12 chief burgesses. The borough returned two members to parliament from this date until the Redistribution Act of 1885, but the other privileges appear to have lapsed in the reign of Elizabeth. Aylesbury evidently had a considerable market from very early times, the tolls being assessed at the time of Edward the Confessor at £25 and at the time of the Domesday survey at £10. In 1239 Henry III. made a grant to John, son of Geoffrey FitzPeter of an annual fair at the feast of St Osith (June 3rd), which was confirmed by Henry VI. in 1440. Queen Mary's charter instituted a Wednesday market and fairs at the feasts of the Annunciation and the Invention of the Holy Cross. In 1579 John Pakington obtained a grant of two annual fairs to be held on the day before Palm Sunday and on the feast of the Invention of the Holy Cross, and a Monday market for the sale of horses and other animals, grain and merchandise.