The Mayan people of Mexico have a radically different concept of illness than that of western countries. In the absence of any formal psychiatric service in their area, the people continue to rely on the interventions of the traditional healers, which include the use of herbal medicines, prayers and magico-religious rituals. A case history of a Mayan patient with a chronic psychotic illness is described, which illustrates the gulf in concepts of mental illness that exists between Western and folk cultures. These cultural differences may have a profound impact on the application of modern psychiatric interventions in developing countries.