Capel Dyddgen is thought to have originally been named Capel Llyddgen and to have originated in the thirteenth century. In 1355-1356 the chapel, along with St Cyndeyrn's Church, Llangynderyn (NPRN 310030) and 'Llangenhython' was granted to New College, Leicester. It is also noted as one of three chapels mentioned in documents of 1358, where it is referred to as Llanlothegeyn. The other two chapels referred to are Llangynderyn and Llangynheiddon. The chapel, together with a small area of land surrounding it, is bordered by minor roads on its north, east and west sides. The chapel is situated some 140m south of Capel Dyddgen Farm.

Capel Dyddgen is also one of three chapels (the others being Capel Bigawdin (NPRN 100629) and Capel Herbach (NPRN 303927) )described in Archaeologia Cambrensis as being in a straight line, within some three miles of one another, following the eastern side of the Gwendraeth Valley at its northen (or upper) end.

In 1894 the chapel was noted to be in ruinous condition, with most of the walls having fallen. The chancel measurements are given as 20ft x 15ft 0r 20ft x 12ft 6in (sources differ). Measurements of the nave are given as 34ft x 12ft 6in. One pointed lancet window remained in the middle of the north wall of the nave. Measurements of the window are given as 27in height x 6in to 25in (splayed) external width. It is possible that there were three single lancet windows to either side of the nave. The tower was noted to be ivy-covered and standing to almost its full height, although a huge cleft was noted in its west wall. The tower was described as having had two stages, and to have been battlemented. The first stage was noted to have been vaulted, with the second stage having had an opening which commanded a view of the chancel.

Sources include:
Cambria Archaeology, 2000, Carmarthenshire Churches, gazetteer, 48
Kay, R.E. 1952, 'Capel Llydogem, Llangendeirne, Carmarthenshire' R.E. Kay notebooks
Tierney, H.C, 1894, 'Unexplored Ecclesiastical Ruins in Carmarthenshire', Archaeologia Cambrensis

N Vousden, RCAHMW, 24 September 2012