The author of this study aims to explore people's perceptions of the cause of illnesses in the Democratic Republic of Congo using qualitative methods, namely case studies and focus group discussions, to gather data from participants. He identifies seven main categories of causes of illnesses and describes the relations between them. The local concept of the causes of illnesses does not absolutely respect the biomedical framework. As the popular saying puts it, Congolais hakufi na microbe, meaning "Congolese people do not die by microbes." The perception of witchcraft is strong as a cause of illness among the Bira of Mobala and the Nande of Mukulia. The author argues that health professionals should take this view into account instead of rejecting it.