Radiesthesia is the paranormal or parapsychological ability to detect "radiation" within the human body. According to the theory, all human bodies give off unique or characteristic "radiations" as do all other physical bodies or objects. Such radiations are often termed an "aura".

A practitioner of radiestheisa believes in his or her ability to detect the interplay of these radiations. Thus radiesthesia is cited as the explanation of such phenomena as dowsing by rods and pendulums in order to locate buried substances, diagnose illnesses, and the like.

The term radiesthesia first entered English in the 1930s and was borrowed from the earlier French radiésthesie. The English word is a compound of the prefix radi(o)-, referring to radiation and the rare term aesthesia meaning "perception by the senses", or "the capacity for feeling or sensation", which comes from the ancient Greek aisthesis "a perceiving".

Dr. Solcol W. Tromp wrote about radiesthesia in his 1949 book Psychical Physics. This reference has a bibliography of over 700 titles relating to dowsing and radiesthesia.

Gerald Gardner, in his book Witchcraft Today, 1954, refers to his own anecdotal experiences with radiesthesia as evidence supporting the existence of "Witch Power".

The Pendulum is a monthly publication devoted to radiesthesia. There are other periodicals, publications, books, societies and numerous websites on the topic.

Scientific tests by establishment figures claim to disprove the effectiveness of radiesthesia.