The River Wylye (pronounced /ˈwaɪli/ wy-lee) is a classic southern England chalk stream; champagne clear water flowing over gravel. Consequently, it is popular with anglers keen on fly fishing.
It rises below the White Sheet Downs just south of Maiden Bradley in Wiltshire, and after flowing through the Deverill valley, forms the southern edge of Warminster. It then heads generally east south east, forming the Wylye Valley, into which the A36 road and the Wessex Main Line are also squeezed. The river passes through the parishes of Norton Bavant, Heytesbury, Knook, Upton Lovell, Boyton, Codford, Wylye and Wilton, to the near the southern edge of Salisbury Plain, and is fed by ephemeral, winterbourne streams so water flow can vary.
The river forms part of the River Avon catchment. At Wilton it joins the River Nadder and eventually drains to the sea at Christchurch as part of the River Avon.
The Wylye valley is a picturesque valley dotted with small chocolate box villages composed of thatched cottages and stone-built pubs.
Both Wilton and Wiltshire (Wilton – shire) are named after the river.