Religion remains a powerful influence on notions of health and disease.1 One Islamic concept that has entered into western mythology is that of the jinn or genies, as in the story of Aladdin. However, according to Islamic belief, jinn are real creatures that form a world other than that of mankind, capable of causing physical and mental harm to human beings. An example of such harm is possession.2,3 As defined by Littlewood,4 possession is the belief that an individual has been entered by an alien spirit or other parahuman force, which then controls the person or alters that person's actions and identity. To the observer, this would be manifested as an altered state of consciousness. In the UK, jinn possession is most likely to be seen among people from Pakistan, Bangladesh, the Middle East or North Africa.4 Some commentators claim that possession is a culture-bound syndrome but others argue that, although the manifestations may differ according to culture, the underlying theme is always the same.5 According to Whitwell and Barker,6 the word possession is used in two different ways. The first refers to 'true' possession invoking the supernatural. The second, which makes no such assumptions, has been applied to several different states. One example of the second is a syndrome consisting of clouding of consciousness, changed demeanour and tone of voice and subsequent amnesia. Another is a trance that may be induced deliberately in a certain cult setting. According to Prins,7 true possession consists of occult experience, invitation and unknown influences. Very little has appeared on jinn possession in medical publications. Here we describe cultural and religious and psychiatric aspects and offer guidance on management in clinical practice.