Nave exposed rubble stone walls, later C19 roof has two tie-beam trusses with crown posts up to collars and axial collar-purlin, the crown posts with arched braces on all four sides. Stone voussoirs to splayed window reveals: three lancets to W, none to N, three to S with segmental-pointed head to door surround. Nave E wall is battered at base and crossing arch is off-centre, N wall appears to abut to E wall. Crossing has round arches with stone voussoirs on square piers to W and E, walling to S and N, pierced on S by a low round-arched doorway with keystone, and on N by a tall pointed doorway with stone voussoirs and C19 baize-covered doors. Later C19 beams and corbels to bell-floor, one corbel possibly ancient. S transept has plastered walls, and plain collar-rafters to roof, one pegged original, possibly C18. Taller segmental pointed reveal on N wall backing onto entry from crossing, but taller than crossing round arch. E wall late C19 or C20 large pointed door. Squint at NE corner into chancel.
N transept has plastered walls, C19 windbraced roof with two collar trusses, one with heavy tie-beam. On S wall is 1884 gallery providing access to bell-floor of crossing tower. Pointed altar recess on E wall, framing very narrow pointed light. Squint at SE corner into chancel. Battered base to S wall.
One step into chancel, which has similar roof to nave with two tie beams. Plastered walls with three lancets each side, C19 flush sills, and stepped triplet to E, the sills deeply sloped down to moulded course. Corbel on opposite sides of chancel, either for a rood-beam or statue. Chancel W wall has two crude shields said to relate to the inscription stone 'This steeple was newly erected and made in Apriel anno dom 1629 William Havard Gent and William Griffith Gent then churchwardens EW'. Cambered head to S door. Pointed stone piscina on S wall, renewed in C19. Two steps to sanctuary with C19 tiled pavement.
Fittings: Massive and crude bowl font of tooled stone set on ashlar pedestal, possibly from elsewhere, but medieval. Pedestal is square with sides splayed inwards towards foot, and with big angle chamfers, stopped before top corners. Modern plinth. C19 hardwood pews of good quality with simply moulded bench ends. Large oak pulpit of 1905 with ornate pierced tracery to panels, inscribed as memorial to Giraldus. Oak eagle lectern 1903. C19 chancel stalls with band of pierced cusped squares along frontals. C19 altar rails on twisted brass standards.
Memorials: Crossing S wall: Thomas Morgans of Felin Newydd, Llandevalle, died 1814, painted marbling with two oval plaques side-by-side, and obelisk top with urn, signed Hughes; David Williams of Llanfrynach, died 1823, oval with painted marbling and shield plaque, by T. Phillips of Talgarth. S transept E wall John Williams of Upper Penwain died 1855 with urn above; S wall Roger Williams of Penwain Uchaf died 1833, painted marbling with reeded pilasters, signed ?Giles; W wall Thomas Jones of Gwarcae died 1864 and Ann Davies died 1848.
Inscribed stones: In S porch are the two C10-11 carved pieces retrieved from the fabric of the church in the restoration, said to be possibly parts of the same cross shaft. Also here is the Celtic-cross inscribed stone with incised Gothic letters. In the N transept is preserved the rough 2-handled bowl found in 1859, possibly a stoup, also here is the C12 piscina with rope-moulded square bowl on quatrefoil stem, retrieved from the chancel E gable.