Disparities in underlying theoretical principles and methods of practice between Guajiro traditional medicine and Western medicine have seriously inhibited acceptance of Western medicine among the Guajiro of VEnezuela. Investigation of traditional Guajiro medicine discloses that 2 main disease categories are distinguished. In the less serious cases an assortment of home remedies are pragmatically applied, while in the more serious cases the ultimate cause of the illness must be determined by a shaman in consultation with auxiliary spirits before a treatment can be proposed. The treatment methods and social relationship between practitioner and patient are very different in Guajiro and Western medicine. The process of acculturation has affected the Guajiro in varying degrees; given present diversity it would be difficult to design a medical program suitable for all Guajiro. Sensitivity of Western practitioners working among the Guajiro to native medical theory would help insure that the recommended treatments were actually understood and carried out.