St Aelhaiarn's Church is an active parish church in the village of Guilsfield, Powys, Wales. The village lies 3 miles to the north of Welshpool. The present church dates mainly from the 14/15th centuries, although parts may date back to the 12th. It was restored by George Edmund Street in 1877–1879. The church is designated by Cadw as a Grade I listed building. Its churchyard, which contains a group of ancient yew trees, is designated at Grade II* on the Cadw/ICOMOS Register of Parks and Gardens of Special Historic Interest in Wales.