This essay aims to explore and answer if the horror movies about exorcism stays true to the historical practices of the ritual. Or if the creators of these films made it all up. But also to see how the ritual has been portrayed in these movies over the years. Therefore I chose to analyse four different movies that is in different historic periods of the horror movie genre. Among these movies is the classic movie that started it all, The Exorcist. The other movies is representing periods that came after, with this essay we can also gather how society sees the rite of exorcism. The essay is going to present the history of the ritual, the various symptoms of possession and the classifications of getting an approved exorcism. We will focus on the roman-catholic tradition of this ritual, mainly because it is the version that the movies take most of their inspiration from.