Churches in Killarney have been targeted in broad daylight over the last number of months, including the rural Muckross Church near the Killarney National Park with money being taken from the collection box.
Killarney parish priest Fr Kieran O’Brien recently said rural churches are still open each morning so people can drop in for a quiet prayer, but they are vulnerable.
It is understood gardaí are investigating a number of incidents concerning church burglaries.
There are 53 parishes in the Diocese of Kerry — 44 in Co Kerry and nine in Co Cork.
Many parishes have two or three churches, a small number have one church, and one parish has four.
Parish committees have been asked to review security procedures "with a view to ensuring that reasonable precautions are in place to protect Parish property", a spokeswoman for the diocese said.
Parishes have been advised that valuable religious items and artifacts must be stored away in unmarked and secure cabinets, safes, or storage rooms when not in use.
They have also been reminded that security is a requirement under the Parish Policy of Insurance. Installation of outdoor perimeter lighting and motion-activated lights are among the suggestions, alongside other measures such as making sure that all doors and windows are locked when the building is closed.
Other advice includes installing a security alarm system and the installation of CCTV systems.
The advice comes as the diocese has been left to deal with an exodus of priests due to retirements.
Bishop of Kerry Ray Browne warned that more churches will be without weekend Masses due to the number of priests set to hit retirement age in Kerry.
Already 15 of its 53 parishes are without priests. Currently, a "meitheal" system operates with parishes grouped into pastoral areas and priests operating on a rota basis to ensure churches have weekly Masses.
Last month, the reported that the diocese is laying the groundwork for a new kind of church with laity at its core.
This shift from a priest-dependent to people-centred Church will be "radical".
The move is being billed as one of the most dramatic changes the Irish Church has ever encountered, becoming "circular rather than a top-down", in the words of one of the strategists responsible.