Llandysilio 4 was first noted in 1896. It may have come to light during the 1838 restoration of St Tysilio's Church, Llandysilio (NPRN 308656), when it was built into the external south wall of the church (as a quoin at the south-west angle of the nave), along with three inscribed stones (NPRNs 422416, 421733, 422417).

The stone is an incomplete rectangular section-pillar of pale green felsite. Measurements are given as 104m height x 43cm width x 23cm (max) diameter. The carving, thought to date to the 7th to 9th centuries, consists of an outline, equal-arm cross of Maltese type, with sharply splayed cross-arms within a linear ring. The cross is made up of five compass-drawn circles: one at the centre of the cross-head and four others which form the quadrants. The cross-type has no close parallels in the early medieval monuments of western Britain and Ireland.

Sources include:
Edwards, N. 2007, Corpus of Early Medieval Inscribed Stones and Stone Sculpture in Wales

N Vousden, 3 January 2018