An out-of-the-body (OOB) experience is an altered state of consciousness in which the subject claims that he leaves his body, that he sees it and its usual environment from a vantage point apart from it, and that he journeys to distant places before being reunited with his physical self. A classical example is the ecstatic flight of the shaman. A representative sample of OOB experiences, ranging from frankly pathological cases of depersonalization and derealization in delirious, neurotic, and organic cases to two clinically normal subjects, is reviewed. They suggest that OOB experiences derive from the age-old quest for immortality and the need to deny or defy death. At the same time they may occasionally serve as vehicles for so-called psi phenomena. Some of the parapsychological implications of the OOB experience are discussed.