Beliefs in evil spirits and the practice of deliverance from supernatural forces have been widespread throughout history. Many psychological and physical afflictions have been attributed to involuntary demonic possession. Traditional remedies, for those reporting inhabitation by evil spirits, can involve exorcism believed to expel such forces. Similar beliefs may be symptomatic of major mental illness and treatments namely medication and psychotherapy, are frequently recommended. An increasingly secular western world is also seeing growth in non-denominational Christian churches and other faiths, who accept spirit possession and exorcism. Culturally competent mental health professionals, seeking to understand their patients’ world view, may struggle with exorcism, seeing it as an interference to conventional treatment. They may be being unwilling thus to attempt differentiation between possession and mental illness. This paper explores the diversity of views on this topic and points of contention and overlap. The risks and cautions necessary in approaching this issue are stressed.