Celtic Reiki is a version of Japanese Reiki with a New Age Celtic twist. It was created by Martyn Pentecost and further developed by Julie Norman, and employs symbols derived from ogham (an ancient runic script used by some Gaelic tribes). Advocates claim that Reiki energy mimics the frequency of various trees and plants so as to combine the alleged healing energy of Reiki with channeled "ancient wisdom of the Celts."

Many scientists, traditional Chinese medicine practitioners, health professionals and others dispute the effectiveness of Reiki stating that there is no proof or evidence that Reiki energy exists, nor proof that healing beyond that expected from the placebo effect can be achieved by it.