The functions and successes of shamanistic healers are addressed in the context of psychoneuroimmunology, which allows a description of how therapeutic success is achieved via the symbolic manipulation of biological processes. These perspectives reinforce the continued importance of traditional shamanistic healers in the contemporary world. This is illustrated by the activities of a Peruvian healer who utilizes both psychoactive plant substances and a syncretic combination of modem and traditional symbolic therapies. The reliance on a wide range of psychoactive plants, including both psychoactive substances and nonhallucinogenic plants, is shown to be empirically effective in the treatment of disease. This demonstrates the pragmatic and adaptive approaches of these traditional healers and their positive functions in treating a variety of illnesses in today's world.