Interior
Simple church of 2 aisles, with the sanctuary at the E end of the N aisle and a modern enclosed vestry in the NW corner; the chancel is raised by one step and the sanctuary a further 2 steps with a brass rail on shaped brass stanchions with floriate brackets.
The church underwent extensive restoration in the mid C19, and the 2 aisles divided by a simple timber arcade of octagonal posts on stone piers. The arcade is recorded in the Inventory of Merioneth as having a plain entablature made of discarded pews, 2 of which bear the dates 1772 and 1779, now obscured by plaster. The roof has exposed timbers, the S aisle is of 6 roof bays with arch braced chamfered collared trusses, the braces above the collars cusped; between the trusses are moulded timbers following the roofline, possibly the remains of the C16 roof timbers. The N aisle is of 9 roof bays, also with arch braced chamfered trusses with angled braces over the collar; most probably replaced following the fire of 1978, though that over the sanctuary may be one of the re-used C14 trusses.
Fittings are mid C19, the box pews with chamfered angles. The font is to E of the doorway and is an intricately traceried C19 octagonal font with traceried panels and a tall, highly decorative, carved wooden cover.
Glass:
The N wall has a small recessed area which is lit by a single window which bears the image of the patron saint of the church, St Madryn. The E window to S aisle is an early C20 window depicting Jesu Mercy and St David, to Elizabeth Hatton Wood of Pantglas . 1904 and alongside is a bronze tablet to her husband, Richard Henry Wood d.1908. The N aisle has a late C19 window depicting Christ as shepherd to William Williams, Rector of the parish, d.1888.
Memorials:
Between the 2 windows is a slate tablet memorial to Richard Roberts of Tyddyn Du d.1816, his wife Ann d.1828, to Gwen, daughter of Robert Roberts and his wife Margaret d.1859, also Ann their daughter d.1840 and Margaret, his wife, d.1846.
The N wall bears a number of mid and late C19 slate memorials as well as an early C20 bronze tablet; also a slate to the Jones family of Dolgain - Elizabeth Jones d.1840, John d.1849, Robert d.1826, Anne d.1853, Anne d.1853 and William d.1793, also Elizabeth Poole d.1815, Elizabeth Jones d.1846, Elinor d.1853, Frances d.1817, Richard d.1822, Margaret d.1805 and Robert Lloyd Jones d.1890.
Within the recess along the N wall are several mid C19 slate, marble and bronze memorial tablets, also a bronze to John Lloyd of Bryn Llefrith d.1764, and a slate to John Pryse d.1809.
The W wall has a mid C19 slate memorial and a slate which bears the englyn:
Annedd fair sanctaidd noddfa - Gor breiniol / Ger bron Duw a'r dyrfa / Er dim na thyred yma / Y dyn, ond a meddwl dda. / Parch E B Thomas 1899 Eosceiriog.
The S wall bears several slate memorial tablets including one to John Morris of Calgwyn d.1816, his daughter d. 1828, son John d.1845 and wife Sarah d.1847; slate tablet to Maurice Roberts, Gwynfynydd, d.1807, his wife Catherine d.1818, sons David d.1816 and Robert d.1847; and slate tablet to the family of Rhiwgoch - David Davies d.1784, Robert Roberts d.1787, Ann Davies d.1804, Robert Roberts d.1842, Jane, wife of Robert Roberts d.1831, John Roberts d.1845, Jane Roberts d.1852, David Roberts d.1856, Elizabeth Roberts d.1860 and Robert Roberts d.1871.