The study analyzes the traditional beliefs and practices concerning leprosy of the Limba people of Sierra Leone. It shows that this dialectally diverse ethnic group has two views of leprosy and its cause, and two varieties of stigma associated with the disease. The Limba have abandoned their traditional treatments for leprosy in response to an effective leprosy control programme, but retained their traditional world view, including its definition of illness, which holds a person seriously ill only when he has severe pain or disability. Thus, they seek treatment from the programme, but often at a relatively advanced stage of the disease. The study shows that the Limba have reinterpreted the notion of ‘germs’ as introduced by medical workers, and that leprosy control workers have their own misunderstandings of Limba beliefs and practices. The study points the way to improved communication between leprosy workers and Limba patients by focusing on the points at which their views differ, and by identifying concepts within Limba world view that can be adapted by leprosy workers to help convey their message. The study emphasizes the importance of world view as a key to understanding patient attitudes and behaviour in developing countries, and to making valid cross-cultural comparisons, but notes that it can take years for an investigator to understand the world view of a particular culture. It argues that in short-term research projects there is an advantage to working with an anthropologist who has in-depth knowledge of the culture, but who may not be a specialist in medical anthropology.