In the city of Iquitos and its vicinity there is even today a rich tradition of folk medicine. Practitioners, some of whom qualify as shamans, make an important contribution to the psychosomatic health of the inhabitants of this area. Among them there are those called vegetalistas or plant specialists and who use a series of plants called doctores or plant teachers. It is their belief that if they fulfill certain conditions of isolation and follow a prescribed diet, these plants are able to "teach" them how to diagnose and cure illnesses, how to perform other shamanic tasks, usually through magic melodies or icaros, and how to use medicinal plants. Four shamans were questioned about the nature and identity of these magic plants, what are the dietary prescriptions to be followed, how the transmission of shamanic power takes place, the nature of their helping spirits, and the function of the magic melodies or icaros given to them by the plant teachers.