The church has a pre-Romanesque nave with antae and a flat-headed W doorway surrounded by a frame in relief. The chancel was added in the 12thc. The E window is round-headed with a Romanesque moulding. The church was much restored c.1700. There is an ogham stone and an early Christian cross slab in the nave.
Ratass was chosen as the Episcopal see of Kerry at the synod of Rathbreasail (1111), but was replaced by Ardfert by 1117 (Gwynn & Hadcock 1970, 95).