St Ismael's Church is situated within a rectilinear churchyard, immediately north of Rosemarket Rath (NPRN 305262), a defended Iron Age enclosure reused as the site of the medieval castle of Rosemarket Borough. The churchyard may partially overly the silted ditch of the enclosure ? suggestive of early medieval reuse as a cemetery, as known at a number of other Iron Age enclosure sites. The Ismael dedication may have been changed to Leonard for a time during the post-Conquest period. St Leonard's Well (NPRN 32505) lies some 200m to the east-southeast. The church was a parish church during the post-Conquest period, belonging to the Deanery of Rhos. Around 1145 the knights William FitzHait, Robert FitzGodebert and Richard FitzTankard granted the church to the Knights Hospitaller of Slebech Commandery.

The church is a Grade 2 listed building, considered important for its substantial medieval fabric, unusually large squint passage, and key location in the village. The church is constructed of limestone rubble and consists of 3-bayed nave, 2-bayed chancel, north transept/chapel with skew passage and north porch. The nave may date to the 12th century. The square, oolite font bowl may date to the 13th century. The chancel may date to the 14th or 15th century. The church was described as being in a ruinous state in 1640, and in 1674, patron, John Stepney of Pendergast, was ordered to repair the chancel. The north transept and skew passage, and possibly the porch, date to around 1600. The north transept has four medieval corbels associated with a former rood loft. The church was restored in 1856, when the walls were partially rebuilt and build-up in the churchyard around the church was removed. The nave roof was restored at this time, and the church was reseated. The church was again restored in 1891, when the church was reseated again, reroofed and the chancel floor raised. The chancel benching and remains of the rood stair were removed.

Sources include:
Cadw, Listed Buildings Database
Cambria Archaeology, 2000, Pembrokeshire Churches, gazetteer, 48
Cambria Archaeology, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer

N Vousden, 24 October 2018